Sample records for filament winding machine

  1. Differentiation between coronal holes and filament channels from SDO image data using machine learning algorithms

    NASA Astrophysics Data System (ADS)

    Reiss, Martin; Hofmeister, Stefan; DeVisscher, Ruben; Temmer, Manuela; Veronig, Astrid; Delouille, Veronique; Rotter, Thomas

    2015-04-01

    In combination with the Sun's rotation, coronal holes and their associated high speed solar wind streams (HSSs) shape the solar wind distribution in the interplanetary space. The structuring of interplanetary space is especially important for deriving changes in the kinematics of coronal mass ejections. In order to forecast HSSs we empirically relate the fractional coronal hole area to the solar wind speed at 1AU. We apply an automated method for the identification and extraction of coronal hole regions in SDO/AIA 193Å images. Due to the almost equal low intensity of coronal holes and filament channels the intensity-based detection method cannot differentiation filament channels from coronal holes. Hence, to improve the HSS forecasting method we need to distinguish filament channels from coronal holes. Compared to coronal holes, filament channels are regions of closed magnetic field lines along a polarity inversion line and are therefore different in their magnetic field configuration. Acting on this physical background we investigate the benefits of using Haralick's textural features to analyze the intrinsic texture information contained with coronal holes and filament channels in AIA and HMI images. In combination with first order statistics and shape measures, we tested several classifiers to find the most suitable decision rule for a differentiation. In order to evaluate the performance of each classifier the Hanssen-Kuiper skill score, also called True Skill Statistic, was calculated. The results reveal that all classifiers, including Support Vector Machine (SVM), Linear SVM, Decision Tree and Random Forest classifier provide good results in general.

  2. Applied aerodynamics of wind power machines

    Microsoft Academic Search

    R. E. Wilson; P. B. S. Lissaman

    1974-01-01

    Aerodynamics of various types of wind power machines, and advantages and disadvantages of various schemes for obtaining power from the wind are reviewed. Simple, one-dimensional models for various power producing machines are given along with their performance characteristics, and presented as a function of their elementary aerodynamic and kinematic characteristics. Propeller type wind turbine theory is reviewed to level of

  3. Filament winding cylinders. III - Selection of the process variables

    NASA Technical Reports Server (NTRS)

    Lee, Soo-Yong; Springer, George S.

    1990-01-01

    By using the Lee-Springer filament winding model temperatures, degrees of cure, viscosities, stresses, strains, fiber tensions, fiber motions, and void diameters were calculated in graphite-epoxy composite cylinders during the winding and subsequent curing. The results demonstrate the type of information which can be generated by the model. It is shown, in reference to these results, how the model, and the corresponding WINDTHICK code, can be used to select the appropriate process variables.

  4. TRW A-type polyimide resin for filament winding

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Ueda, K. K.

    1974-01-01

    Studies were conducted to select a TRW A-type polyimide resin that would be suitable for fabrication of filament wound reinforced plastics structures. Several different formulations were evaluated after which the P105AC formulation was selected as the most promising. Procedures were developed for preparing P105AC/S-glass roving prepreg and for fabricating filament wound structural composites. Composites were fabricated and then tested in order to obtain tensile and shear strength information. Small, closed-end cylindrical pressure vessels then were fabricated using a stainless steel liner and end-fittings with a P105AC/S-glass polar-wound overwrap. These pressure vessels were cured in an air circulating oven without augmented pressure. It was concluded upon completion of this study that the P105AC resin system is suitable for filament winding; that low void content, high strength composites are obtained by the filament winding process; and that augmented pressure is not required to effect the fabrication of filament wound P105AC composites.

  5. Filament winding S-glass/polyimide resin composite processing studies

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J.

    1974-01-01

    The work performed in selecting a TRW A-type polyimide resin that would be suitable for fabrication of filament wound reinforced plastic structures is described. Several different formulations were evaluated after which the P105AC formulation was selected as the most promising. Procedures then were developed for preparing P105AC/S-glass roving prepreg and for fabricating filament wound structural composites. Composites were fabricated and then tested in order to obtain tensile and shear strength information. Small, closed-end cylindrical pressure vessels then were fabricated using a stainless steel liner and end fittings with a P105AC/S-glass polar wound overwrap. These pressure vessels were cured in an air circulating oven without augmented pressure. It is concluded that the P105AC resin system is suitable for filament winding; that low void content, high strength composites are obtained by the filament winding process; and that augmented pressure is not required to effect the fabrication of filament wound P105AC composites.

  6. Development of controller strategies for a robotized filament winding equipment

    NASA Astrophysics Data System (ADS)

    Lobo, Edgar; Machado, José; Mendonça, João P.

    2013-10-01

    The composites reinforced with continuous fibers of polymeric material are increasingly used in applications where it is essential to reduce weight, mainly due to their high ratio of strength/weight and rigidity/weight. A conventional application are pressure vessels, used for storing liquids or gases subjected to low or high pressure, where the tape continuous fiber-reinforced polymeric matrix material is wound around a mandrel defining the final geometry. In this context the filament winding process is a very attractive process for the production of composite components. For optimal structural performance, and greater weight saving, an optimal path should be adopted, resulting only in axial tension in the longitudinal direction (slip). Such path is the geodesic winding and diverse equipment may be used to guarantee the process automation of the winding. This work herein presented is focused on the study and development of the controller program for a robotized filament winding equipment, taking into account customization of possible trajectories controlling filament winding. The automation of the custom path according to user needs increases exponentially the capabilities, where the use of a robotized solution increases process flexibility and repeatability.

  7. Dual stator winding induction machine drive

    Microsoft Academic Search

    Alfredo R. Muñoz; Thomas A. Lipo

    2000-01-01

    A new dual stator winding induction machine drive is described in this paper. The proposed induction machine consists of a standard squirrel-cage rotor and a stator with two separate windings wound for a dissimilar number of poles. Each stator winding is fed from an independent variable-frequency variable-voltage inverter. The proposed drive offers such advantages as speed sensorless operation, better reliability,

  8. Optimum windings for linear induction machines.

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.

    1973-01-01

    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.

  9. Heat flow analysis in connection with thermoplastic filament winding

    NASA Astrophysics Data System (ADS)

    Brage, Anders; Lamrell, Charles

    1988-04-01

    In thermoplastic filament winding the calculated rate of cooling is found to be in the order of 100000 degr.C/second at the bonding interface. Short range heat flow phenomena are analyzed, and the result provides a simple rule of thumb for practice, together with a winding speed dependant correction for glass and carbon fiber composites. This enables an easy method to calculate the lower temperature limits for the process of continuous welding, as well as the upper temperature limit where resin starved laminates result from excessive resin flow due to heat buildup. The applied model of heat transfer is given in analytical expressions. Calculated results are given in several graphs.

  10. The stress development during filament winding of thick cylinders

    NASA Astrophysics Data System (ADS)

    Hahn, H. T.; Lee, S. S.

    1992-08-01

    The stress development during filament winding of thick composite cylinders has been studied using dry glass fiber tows. The thicknesses of the wound cylinders were more than 38 mm while the aluminum mandrel used had an outside diameter of 58 mm. Circumferential winding was used and the winding tension was varied between 4 and 23 N. The radial pressure measured at the mandrel surface using foil gages increased over the first 6 layers or so of winding, and then stayed constant or even decreased slightly with subsequent winding. Predictions based on elastic analyses were fitted to the data by varying the effective radial modulus. The resulting values of the radial modulus were much less than the circumferential modulus, the latter being more than ten-thousand times greater than the former. Such high anisotropy was responsible for the asymptotic increase of the mandrel pressure with winding. The calculated circumferential stress in the fibers was compressive throughout most of the inner part of the wound cylinder however, its magnitude was rather small. A higher winding tension resulted in a better compaction, and therefore, a smaller effective layer thickness, a higher radial modulus, and higher internal stresses. Under the winding conditions studied in the present work, fiber buckling due to the development of compressive circumferential stress does not appear possible.

  11. Wind power machines receiving fresh wind

    Microsoft Academic Search

    F. Seguier

    1976-01-01

    The history, current status, and future prospects of power generation by wind-activated power plants is surveyed. Vaned wind-power devices similar to those used in ancient Sumer are still in use in Iran today, while European windmills have shifted in function from flour milling to water pumping. The devices are most feasible in isolated locations where dispersed energy sources are needed,

  12. Composite Pressure Vessel Variability in Geometry and Filament Winding Model

    NASA Technical Reports Server (NTRS)

    Green, Steven J.; Greene, Nathanael J.

    2012-01-01

    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.

  13. Intraseasonal variability in the summer South China Sea: Wind jet, cold filament, and recirculations

    E-print Network

    Xie, Shang-Ping

    Intraseasonal variability in the summer South China Sea: Wind jet, cold filament that the blockage of the southwest monsoon by the mountain range on the east coast of Indochina triggers a chain of ocean-atmospheric response, including a wind jet and cold filament in the South China Sea (SCS). We

  14. Optimal flux weakening in surface PM machines using concentrated windings

    Microsoft Academic Search

    Ayman M. EL-Refaie; Thomas M. Jahns

    2004-01-01

    A design approach is presented for achieving optimal flux weakening operation in surface PM synchronous machines by properly designing the machine's stator windings using concentrated, fractional-slot stator windings. This technique makes it possible to significantly increase the machine inductance in order to achieve the critical condition for providing wide speed ranges of constant-power operation. The conditions for optimal flux weakening

  15. Induction Machine Analysis for Arbitrary Displacement Between Multiple Winding Sets

    Microsoft Academic Search

    R. H. Nelson; P. C. Krause

    1974-01-01

    The steps in t he applied voltages of a three-phase, inverter-induction motor drive system cause undesirable pulsations in motortor By using multiple inverters connected to a multiphase machine with appropriate winding displacements, significant improvement in system performance is possible. The winding displacements required, however, are not necessarily the symmetrical displacements used in standard multiphase machines. This paper sets forth an

  16. Development of Induction Machines in Wind Power Technology

    Microsoft Academic Search

    Stefan Soter; R. Wegener

    2007-01-01

    This paper gives an overview of the development of the induction machine as a generator for wind turbines from the middle of the 20th century up to now. After a short history chapter the different energy conversion concepts are presented. At first a squirrel cage machine is direct coupled to the grid (Danish concept). To adjust the machine speed the

  17. Fields of Opportunity: Wind Machines Return to the Plains

    ERIC Educational Resources Information Center

    Sowers, Jacob

    2006-01-01

    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

  18. Partitioning of synchronous machine windings for internal fault analysis

    Microsoft Academic Search

    Peter P. Reichmeider; Dale Querrey; Charles A. Gross; Damir Novosel; Sheppard Salon

    2000-01-01

    This paper discusses a technique for partitioning the stator windings of large synchronous machines, for application to internal fault analysis, and determining corresponding winding inductances. The method employs a direct phase representation, which is shown to reduce to the classical phase representation when the partitioned windings are collapsed

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

    NASA Technical Reports Server (NTRS)

    Phan, A.; Lamalle, J.

    1981-01-01

    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.

  20. A model of the winding and curing processes for filament-wound composites

    Microsoft Academic Search

    Tzeng

    1988-01-01

    A two-dimensional model that describes the winding and curing processes of filament-wound composite structures was developed in two parts. The first part is the cure model which relates the cure temperature, applied at the boundaries of the composite, to the thermal, chemical, and physical processes occurring in the case during cure. For a specified cure cycle, the cure model can

  1. Time dynamics of burst-train filamentation assisted femtosecond laser machining in glasses.

    PubMed

    Esser, Dagmar; Rezaei, Saeid; Li, Jianzhao; Herman, Peter R; Gottmann, Jens

    2011-12-01

    Bursts of femtosecond laser pulses with a repetition rate of f = 38.5MHz were created using a purpose-built optical resonator. Single Ti:Sapphire laser pulses, trapped inside a resonator and released into controllable burst profiles by computer generated trigger delays to a fast Pockels cell switch, drove filamentation-assisted laser machining of high aspect ratio holes deep into transparent glasses. The time dynamics of the hole formation and ablation plume physics on 2-ns to 400-ms time scales were examined in time-resolved side-view images recorded with an intensified-CCD camera during the laser machining process. Transient effects of photoluminescence and ablation plume emissions confirm the build-up of heat accumulation effects during the burst train, the formation of laser-generated filaments and plume-shielding effects inside the deeply etched vias. The small time interval between the pulses in the present burst train enabled a more gentle modification in the laser interaction volume that mitigated shock-induced microcracks compared with single pulses. PMID:22273956

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

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

    The creation of high-strength co-extruded polypropylene (PP) tapes allows the production of recyclable “all-polypropylene” (all-PP) composite products, with a large temperature processing window and a high fibre volume fraction. Available technologies for all-PP composites are mostly based on manufacturing processes such as thermoforming of pre-consolidated sheets. The objective of this research is to assess the potential of filament winding as a manufacturing process for all-PP composites made directly from co-extruded tapes or woven fabric. Filament wound pipes or rings were tested either by the split-disk method or a hydrostatic pressure test in order to determine the hoop properties, while an optical strain mapping system was used to measure the deformation of the pipe surfaces.

  3. Transient model for induction machines with stator winding turn faults

    Microsoft Academic Search

    Rangarajan M. Tallam; Thomas G. Habetler; Ronald G. Harley

    2002-01-01

    A transient model for an induction machine with stator winding turn faults is derived using reference frame transformation theory. A state-space representation of the dynamic equations, suitable for digital simulation is provided. Steady-state equivalent circuits are derived, from which the sequence components of the line currents can be estimated as a function of fault severity. Experimental results are provided to

  4. Rotor blade structure and mounting for vertical axis wind machines

    Microsoft Academic Search

    Lechner

    1981-01-01

    A lightweight simplified economical and efficient sail or rotor blade for a vertical axis wind machine and simplified self-acting restraining means for the blade during rotor operation are disclosed. The rotor structure is characterized by ease of assembly and the absence of need for adjustment and frequent maintenance. Individual rotor blades are attached to vertical axis whips extending above and

  5. Fabrication of low cost composite tooling for filament winding large structures

    NASA Astrophysics Data System (ADS)

    Miller, Timothy S.; Fortin, Christopher J.

    A TQM/concurrent engineering approach has been used to create a low cost filament-winding mandrel for large launch-vehicle structure fabrication. The process involves the fabrication of a low cost/low temperature master model, followed by the building of the mandrel and its backup structure within the master. Mandrels fabricated by these means are able to maintain full vacuum integrity and dimensional stability throughout high-temperature cure cycles; the reduced thermal mass of the mandrel results in part-cure cycles that are shorter than those associated with conventional mandrel materials.

  6. Development and use of an improved filament-winding process model

    NASA Astrophysics Data System (ADS)

    Kokan, Davis Rasheed

    Composite materials are being used to solve an ever-increasing variety of engineering problems because they provide greatly improved mechanical properties and the flexibility to tailor them. A process that is often used to fabricate cylindrical composite structures and other surfaces of revolution is filament-winding. The objective of this research is to develop a model of the filament-winding process. At a time when concurrent engineering philosophy is being accepted and implemented, design should incorporate as much of the manufacturing process as possible. This is critical in a process like filament-winding where the residual stresses associated with fabrication can be as significant as the stresses encountered during service. Thus the optimum design is dependent upon the physical and chemical phenomena that occur throughout manufacture as well as in the service life. Previous filament-winding process models relied on a linear elastic assumption to describe the material behavior during cure. However, it is known that many of today's polymeric resins exhibit a time dependent response even during the cure cycle. A major contribution of this work is the incorporation of this viscoelastic response into the process model. Although these materials and mechanics issues are a major focus, they are incorporated into a comprehensive multidisciplinary process model that includes heat transfer, chemorheology, and compaction. It predicts, as a function of position and time, the temperature, degree of cure, viscosity, and deformation of a thick composite cylinder of arbitrary lay-up as well as the resulting residual stress state. The model is validated through an experimental program consisting of a materials characterization study of an AT-400/Fiberite 934 graphite epoxy composite and the measurement of processing induced strains. Good correlation is achieved between model predictions and experimental results. The various geometric and material input parameters are also investigated to determine their impact and relative importance on the predicted residual stresses. Recommendations for future work such as cure cycle optimization and extension to other material systems and geometries are made.

  7. The Inertial Response of Induction-Machine-Based Wind Turbines

    Microsoft Academic Search

    Alan Mullane; Mark O'Malley

    2005-01-01

    The inertial response of a generator is influenced by the sensitivity of the generator's electromagnetic torque to changes in the power system frequency. This paper deals with the inertial response of wind turbines employing induction-machine-based generators. A model of a field-oriented controlled doubly fed induction generator based on a fifth-order induction-generator model is described. The proposed model is implemented in

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

    SciTech Connect

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

    2002-05-20

    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.

  9. Processing parameters for filament winding thick-section PEEK/carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Colton, J.; Leach, D.

    1992-12-01

    The consolidation pressure and winding speed for thermoplastic filament winding were studied. Thermoplastic composite parts were manufactured from tape prepreg (APC-2); powder-coated, semi-consolidated towpreg; and commingled fiber towpreg. The material used was carbon fiber (AS-4) (60 vol pct) in a PEEK matrix. The parts made were open-ended cylinders of the three materials, 177.8-mm ID, 228.6 mm long, 17 plies thick with a 0 deg lay-up angle; and rings, 50 plies of APC-2 thick, 6.35 mm wide (one strip wide), 177.8-mm ID, and a lay-up of 0 deg. Their quality was determined by surface finish and void percentage. The tubes made from APC-2 appeared to have the best quality of the three prepregs. For the rings, the speed of lay-down had a significant effect on both the final width of the parts and on the percentage of voids. The pressure of the roller had a significant effect on the final widths at a 99 percent confidence level, but a significant effect on the percentage of voids at only a 95 percent confidence level.

  10. Wind

    NSDL National Science Digital Library

    National Energy Education Development (NEED) Project

    2003-01-01

    This document examine wind power as an energy resource. The reading will define wind and discuss topics such as (1) The history of wind machines, (2) Today's windmills, and (3) Types of wind machines. This resource is structured as an informational handout to supplement your energy activities or to generate discussion questions. Copyright 2005 International Technology Education Association

  11. Vector control of the Brushless Doubly-Fed Machine for wind power generation

    Microsoft Academic Search

    Shiyi Shao; Ehsan Abdi; Richard McMahon

    2008-01-01

    The brushless Doubly-Fed Machine (BDFM) shows commercial benefits in the wind power generation. This paper presents a vector control scheme for the BDFM operating as a variable speed generator (VSG). The proposed vector controller is developed on the power winding stator flux frame, and can be used to control both speed and reactive power. The machine model and the control

  12. Optimal flux weakening in surface PM machines using fractional-slot concentrated windings

    Microsoft Academic Search

    Ayman M. EL-Refaie; Thomas M. Jahns

    2005-01-01

    A design approach is presented for achieving optimal flux-weakening operation in surface permanent-magnet (SPM) synchronous machines by properly designing the machine's stator windings using concentrated, fractional-slot stator windings. This technique makes it possible to significantly increase the machine inductance in order to achieve the critical condition for providing wide speed ranges of constant-power operation. The conditions for optimal flux weakening

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

    NASA Astrophysics Data System (ADS)

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

    1994-06-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  15. Broken Bar Detection in Synchronous Machines Based Wind Energy Conversion System 

    E-print Network

    Rahimian, Mina Mashhadi

    2012-10-19

    Electrical machines are subject to different types of failures. Early detection of the incipient faults and fast maintenance may prevent costly consequences. Fault diagnosis of wind turbine is especially important because ...

  16. Broken Bar Detection in Synchronous Machines Based Wind Energy Conversion System

    E-print Network

    Rahimian, Mina Mashhadi

    2012-10-19

    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...

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

    Microsoft Academic Search

    Markus A. Poller

    2003-01-01

    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

  18. Experimental verification of optimal flux weakening in surface PM Machines using concentrated windings

    Microsoft Academic Search

    Ayman M. EL-Refaie; Thomas M. Jahns; Patrick J. McCleer; John W. McKeever

    2006-01-01

    Previous analytical work has shown that it is possible to design surface permanent-magnet (SPM) machines using fractional-slot concentrated windings to achieve wide speed ranges of constant power operation by satisfying the optimal flux-weakening condition. This paper presents a 6-kW 36-slot\\/30-pole concentrated winding prototype SPM machine that has been designed using a closed-form analytical technique developed specifically for this class of

  19. Power smoothing in wind generation systems using a sensorless vector controlled induction Machine driving a flywheel

    Microsoft Academic Search

    Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

    2004-01-01

    This paper presents a novel control strategy for power smoothing in generation systems in which power flow variations can occur. These variations are the norm in wind energy generation. The system is based on a sensorless vector controlled induction machine driving a flywheel. The induction machine is controlled to operate in a wide speed range by using flux weakening above

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

    NASA Astrophysics Data System (ADS)

    Gündo?du, Tayfun; Kömürgöz, Güven

    2012-08-01

    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.

  1. Electromagnetic Analysis of Axial-Flux Permanent Magnet Synchronous Machines With Fractional Windings With Experimental Validation

    Microsoft Academic Search

    Roberto Di Stefano; Fabrizio Marignetti

    2012-01-01

    Axial-flux permanent magnet (PM) synchronous machines are suitable for direct drive applications. Axial-flux PM synchronous machines with fractional windings provide high power density, low torque ripple, and sinusoidal phase voltages, but suffer from high rotor losses due to stator field harmonics and slotting. This paper formulates an electromagnetic model based on the polar coordinate representation of the air-gap magnetic field.

  2. On the effect of winding parallel paths in synchronous permanent magnet electric machine drives

    Microsoft Academic Search

    D. M. Ionel; I. P. Brown

    2010-01-01

    The described study involved interior permanent magnet (IPM) motors with distributed and concentrated (non-overlapping) stator windings. The machines were operated with sine-wave current-regulated power electronic drives. A coupled finite element model was used for the electromagnetic field and electric circuit analysis. Special instrumentation was employed for the measurement of 3D forces. It is shown that stator winding parallel paths can

  3. Investigation on Pole-Slot Combinations for Permanent-Magnet Machines with Concentrated Windings

    Microsoft Academic Search

    F. Libert; J. Soulard

    The aim of this paper is to find the best concentrated windings layouts for high pole number permanent-magnet (PM) machines. Pole and slot numbers are varied from 4 to 80 and 6 to 90 respectively. Among all the pole\\/slot combinations, those giving the highest winding factors are provided. Harmonics in the magneto-motive force (MMF), torque ripple and radial magnetic forces

  4. Controllable d.c. power supply from wind-driven self-excited induction machines

    Microsoft Academic Search

    D. B. Watson; J. Arrillaga; T. Densem

    1979-01-01

    A variable-speed generating system is described which uses a 3-phase squirrel-cage induction machine with self-excitation capacitors. The variable-frequency\\/variable-voltage generated is then fed through a 3-phase controlled rectifier to provide a d.c. supply at constant voltage. The proposed scheme is suitable for wind power sources as it allows wide changes in wind turbine speed and, at all speeds, optimum generating power

  5. System for maintaining the alignment of mandrels in filament winding operations

    DOEpatents

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

    1984-01-01

    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.

  6. System for maintaining the alignment of mandrels in filament winding operations

    DOEpatents

    Robinson, S.C.; Dodge, W.G.; Pollard, R.E.

    1983-10-12

    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.

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

    NASA Astrophysics Data System (ADS)

    Mijatovic, Nenad; Jensen, Bogi Bech

    2014-05-01

    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.

  8. Modeling of stator teeth-tip iron losses in fractional-slot concentrated winding surface PM machines

    Microsoft Academic Search

    P. B. Reddy; T. M. Jahns

    2009-01-01

    This paper presents a model for estimating the iron losses in the stator teeth tips of surface permanent magnet (SPM) machines with fractional-slot concentrated windings based on simplified semi-analytical solutions for the machine flux densities. This model is being developed for use in machine design optimization software that analyzes very large numbers of candidate designs. Tooth tip design details are

  9. A Mars 1 Watt vortex wind energy machine

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  10. A simulator of winding machine controller using LabView environment

    Microsoft Academic Search

    Chao-huang Wei; Chih-hsing Wu

    2004-01-01

    Winding systems are major components in a wide variety of industrial factories for metal sheet or web conveyance, papermaking or polymer film extrusion processes. In those systems, it is clear that the quality of products and the performance of systems are determined by tension and velocity control of the moving material. Although the machine is classified as a nonlinear system

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

    E-print Network

    Mobasher, Barzin

    . The electrical and electronics components consist of several servo-motors, encoders, limit switches controls two servo-motors. Configuration of the servo-motors determines the winding, pulling, and guidance. A direct drive servo-motor, provides the necessary torque for positioning the table. An optical encoder

  12. A novel analytical method for prediction of the broken bar fault signature amplitude in induction machine cage rotor and synchronous machine damper winding

    Microsoft Academic Search

    Mina M. Rahimian; Seung Choi; Karen Butler-Purry

    2011-01-01

    In this paper, the rotor failures in squirrel cage induction machines and the damper winding failures in synchronous machines are analytically investigated. The quantitative evaluation of the stator current left sideband component (LSBC) amplitude is discussed and its correlation with the number of broken damper bars is derived. Unlike the cage rotor of an induction motor, the damper bars are

  13. Application of extreme learning machine for estimation of wind speed distribution

    NASA Astrophysics Data System (ADS)

    Shamshirband, Shahaboddin; Mohammadi, Kasra; Tong, Chong Wen; Petkovi?, Dalibor; Porcu, Emilio; Mostafaeipour, Ali; Ch, Sudheer; Sedaghat, Ahmad

    2015-06-01

    The knowledge of the probabilistic wind speed distribution is of particular significance in reliable evaluation of the wind energy potential and effective adoption of site specific wind turbines. Among all proposed probability density functions, the two-parameter Weibull function has been extensively endorsed and utilized to model wind speeds and express wind speed distribution in various locations. In this research work, extreme learning machine (ELM) is employed to compute the shape (k) and scale (c) factors of Weibull distribution function. The developed ELM model is trained and tested based upon two widely successful methods used to estimate k and c parameters. The efficiency and accuracy of ELM is compared against support vector machine, artificial neural network and genetic programming for estimating the same Weibull parameters. The survey results reveal that applying ELM approach is eventuated in attaining further precision for estimation of both Weibull parameters compared to other methods evaluated. Mean absolute percentage error, mean absolute bias error and root mean square error for k are 8.4600 %, 0.1783 and 0.2371, while for c are 0.2143 %, 0.0118 and 0.0192 m/s, respectively. In conclusion, it is conclusively found that application of ELM is particularly promising as an alternative method to estimate Weibull k and c factors.

  14. Analysis of a single-phase induction machine with a shifted auxiliary winding

    SciTech Connect

    Walls, T.A. [Emerson Motor Co., St. Louis, MO (United States). Specialty Motor Div.] [Emerson Motor Co., St. Louis, MO (United States). Specialty Motor Div.; Sudhoff, S.D. [Univ. of Missouri, Rolla, MO (United States). Dept. of Electrical Engineering] [Univ. of Missouri, Rolla, MO (United States). Dept. of Electrical Engineering

    1996-12-01

    This paper extends the method of multiple reference frames to the analysis of asymmetrical induction motors with non-orthogonal stator windings, with particular emphasis on the permanent split capacitor (PSC) machine. The predictions of the method are verified by comparison to both experimental results and to results obtained using a machine variable computer simulation. Once verified, the method is used to derive the transfer function relating rotor speed to load torque disturbance, which is of particular interest when analyzing PSC machines driving compressor loads. It is shown that the transfer function exhibits a distinct resonant point, and that the magnitude of the resonant peak increases as the motor approaches synchronous speed. It is also shown that the magnitude of the resonant peak may be lowered by increasing rotational inertia or rotor resistance.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

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

    SciTech Connect

    Simoes, M.G. [Univ. of Sao Paulo (Brazil)] [Univ. of Sao Paulo (Brazil); Bose, B.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Electrical Engineering] [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Electrical Engineering; Spiegel, R.J. [Environmental Protection Agency, Research Triangle Park, NC (United States), Air and Energy Engineering Research Lab.] [Environmental Protection Agency, Research Triangle Park, NC (United States), Air and Energy Engineering Research Lab.

    1997-01-01

    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 vector control in the inner loops. A fuzzy controller tracks the generator speed with the wind velocity to extract the maximum power. A second fuzzy controller programs the machine flux for light load efficiency improvement, and a third fuzzy controller gives robust speed control against wind gust and turbine oscillatory torque. The complete control system has been developed, analyzed, and validated by simulation study. Performances have then been evaluated in detail.

  17. Windings Temperature and Loss of Life of an Induction Machine Under Voltage Unbalance Combined With Over or Undervoltages

    Microsoft Academic Search

    P. Gnacinski

    2008-01-01

    This paper deals with the effect of simultaneous voltage unbalance and over- or undervoltage on windings temperature and thermal loss of life of an induction cage machine. The presented results of investigations are based on the experiment and thermal modeling. The influence of an angle of the complex voltage unbalance factor (CVUF) on machine heating is considered. The effect of

  18. Performance Analysis of an Induction Machine-Based Flywheel Energy Storage System Associated to a Variable-Speed Wind Generator

    Microsoft Academic Search

    Gabriel CIMUCA; Mircea M. RADULESCU; Christophe SAUDEMONT; Benoît ROBYNS

    The flywheel energy storage systems (FESSs) are suitable for improving the quality of the electric power delivered by the wind generators and to help these generators to contribute to the ancillary services. This paper investigates the energetic performances of a low-speed FESS with a classical squirrel-cage Induction Machine (IM) in the aim of its association to a wind generator.

  19. Failure assessment of aluminum liner based filament-wound hybrid riser subjected to internal hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Dikshit, Vishwesh; Seng, Ong Lin; Maheshwari, Muneesh; Asundi, A.

    2015-03-01

    The present study describes the burst behavior of aluminum liner based prototype filament-wound hybrid riser under internal hydrostatic pressure. The main objective of present study is to developed an internal pressure test rig set-up for filament-wound hybrid riser and investigate the failure modes of filament-wound hybrid riser under internal hydrostatic burst pressure loading. The prototype filament-wound hybrid riser used for burst test consists of an internal aluminum liner and outer composite layer. The carbon-epoxy composites as part of the filament-wound hybrid risers were manufactured with [±55o] lay-up pattern with total composite layer thickness of 1.6 mm using a CNC filament-winding machine. The burst test was monitored by video camera which helps to analyze the failure mechanism of the fractured filament-wound hybrid riser. The Fiber Bragg Grating (FBG) sensor was used to monitor and record the strain changes during burst test of prototype filament-wound hybrid riser. This study shows good improvements in burst strength of filament-wound hybrid riser compared to the monolithic metallic riser. Since, strain measurement using FBG sensors has been testified as a reliable method, we aim to further understand in detail using this technique.

  20. The effect of wind exposure and filamentous algae on the distribution of surf zone macroinvertebrates in Lake Esrom, Denmark

    Microsoft Academic Search

    Klaus P. Brodersen

    1995-01-01

    Distribution and composition of the epilithic macroinvertebrate fauna was studied on 21 different sites situated in the surf zone of Lake Esrom. A relative degree-of-exposure (windinduced wave activity) was calculated for each station from the specific number of wind days, wind velocity and a measured wind fetch. Macroinvertebrate abundance averaged 20 200 ind. m-2 stone bottom, and was composed primarily

  1. Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines

    SciTech Connect

    El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

    2008-01-01

    This paper presents a modified vector control algorithm for a fractional-slot concentrated-winding surface permanent magnet (SPM) machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. By increasing the amplitude of the negative d-axis current, the resulting increase in the stator copper losses can be more than offset by the reduction in the iron core losses achieved by lowering the stator d-axis flux amplitude. The effectiveness of this technique has been demonstrated using both analytical models and finite element analysis for a 55-kW (peak) SPM machine design developed for a demanding set of traction drive performance requirements. For this example, the modified control strategy increases the partial-load efficiency at 20% of rated torque by > 6% at 2000 r/min compared to the maximum torque/ampere algorithm, making the machine much more attractive for its intended application.

  2. Modified vector control algorithm for increasing partial-load efficiency of fractional-slot concentrated-winding surface PM machines

    SciTech Connect

    El-Refaie, Ayman M [ORNL; Jahns, Thomas M [ORNL; Reddy, Patel [University of Wisconsin; McKeever, John W [ORNL

    2006-01-01

    This paper presents a modified vector control algorithm for a fractional-slot concentrated-winding surface PM machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. By increasing the amplitude of the negative d-axis current, the resulting increase in the stator copper losses can be more than offset by the reduction in the iron core losses achieved by lowering the stator d-axis flux amplitude. The effectiveness of this technique has been demonstrated using both analytical models and finite element analysis (FEA) for a 55 kW (peak) surface PM machine design developed for a demanding set of traction drive performance requirements. For this example, the modified control strategy increases the partial-load efficiency at 20% of rated torque by >6% at 2000 rpm compared to the maximum torque/amp algorithm, making the machine much more attractive for its intended application

  3. Fuzzy logic based intelligent control of a variable speed cage machine wind generation system. Report for January 1994-June 1995

    SciTech Connect

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

    1995-10-01

    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 vector control in the inner loops. A fuzzy controller tracks the generator speed with the wind velocity to extract the maximum power. A second fuzzy controller programs the machine flux for light load efficiency improvement, and third fuzzy controller gives robust speed control against wind gust and turbine oscillatory torque. The complete control system has been developed, analyzed, validated by simulation study, and then performances have been evaluated in detail.

  4. Helical filaments

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  5. Damages of windings of a three-phase slip-ring induction machine having parallel paths in the stator or in the rotor

    Microsoft Academic Search

    S. Rawicki

    1988-01-01

    Contents The following damages of a three-phase slip-ring induction machine having parallel paths in the stator or in the rotor are analysed in the paper: break in a parallel path of the stator or the rotor winding, internal short-circuit in the stator winding, earth fault of the stator winding. The mathematical model of asymmetrical states is presented. For the case

  6. Magnetically driven filament probe

    SciTech Connect

    Schmid, A.; Herrmann, A.; Rohde, V.; Maraschek, M.; Mueller, H. W. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

    2007-05-15

    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.

  7. An Efficient Wind–Photovoltaic Hybrid Generation System Using Doubly Excited Permanent-Magnet Brushless Machine

    Microsoft Academic Search

    Chunhua Liu; K. T. Chau; Xiaodong Zhang

    2010-01-01

    With ever-increasing concerns on energy issues, the development of renewable energy sources is becoming more and more attractive. This paper first reviews both the wind power and photovoltaic (PV) power generation techniques and their maximum-power-point tracking (MPPT) methods. Then, a new stand-alone wind-PV hybrid generation system is proposed for application to remote and isolated areas. For the wind power generation

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

    ERIC Educational Resources Information Center

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

    2013-01-01

    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…

  9. An online stator winding resistance estimation technique for temperature monitoring of line-connected induction machines

    Microsoft Academic Search

    Sang-Bin Lee; Thomas G. Habetler

    2003-01-01

    A new technique for stator-resistance (Rs)-based thermal monitoring of small line-connected induction machines is proposed in this paper. A simple device is developed for injecting a small DC signal into line-connected induction machines for estimation of Rs. The proposed DC injection device is capable of intermittently injecting a controllable DC bias into the motor with very low power dissipation. Experimental

  10. Nonlinear analysis of a permanent magnet synchronous machine with nonsinusoidal stator winding currents

    Microsoft Academic Search

    M. V. K. Chari; J. D’Angelo; G. Bedrosian; T. W. Neumann

    1985-01-01

    Permanent magnet synchronous machines and induction motors are often required to operate on-line starting or inverter-fed systems, which results in nonsinusoidal stator currents. These, in turn, give rise to undesirable harmonics and power losses which degrade motor performance. In this paper a time-domain analysis is presented for evaluating the magnetic field distribution in the two-dimensional cross section of the machine

  11. Application of the AC Commutator Machine in Wind Energy Conversion Systems 

    E-print Network

    El-Jamous, Sami Georges

    1981-01-01

    ( with respect to the wind velocity vector V. The forces brought into play are the thrust T and the driving force T . The latter causes the blade motion at velocity v. The relative velocity is then: V = V-v R at the "angle of attack" n to the active surface.... Available power versus ~iud speed. 60 Wind-Turbine Rotor Characteristics Test curves on a 10-meter diameter f~d-blade angle wind turbine from Reference Li] are shown in figure 20. They indicate the variation of shaft power, P, with rotational speed, mt...

  12. Design and Control Strategies of an Induction-Machine-Based Flywheel Energy Storage System Associated to a Variable-Speed Wind Generator

    Microsoft Academic Search

    Gabriel Cimuca; Stefan Breban; Mircea M. Radulescu; Christophe Saudemont; Benoit Robyns

    2010-01-01

    Flywheel energy storage systems (FESSs) improve the quality of the electric power delivered by wind generators, and help these generators contributing to the ancillary services. Presently, FESSs containing a flux-oriented controlled induction machine (IM) are mainly considered for this kind of application. The paper proposes the direct torque control (DTC) for an IM-based FESS associated to a variable-speed wind generator,

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

    Microsoft Academic Search

    Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

    2001-01-01

    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

  14. A new Approach for Electrical Machine Winding Insulation Monitoring by Means of High Frequency Parametric modelling

    Microsoft Academic Search

    W. Liu; E. Schaeffer; D. Averty; L. Loron

    2006-01-01

    This paper investigates a new approach for stator winding insulation diagnosis. Unlike conventional methods such as insulation resistance tests or partial discharge monitoring, this approach is based on the effective use of parametric modelling and identification. The guiding principle consists in modelling the high-frequency input-output behavior of the winding ground-wall insulation system. The originality and the difficulty of our work

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

    SciTech Connect

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

    2007-05-01

    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.

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

    SciTech Connect

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

    2007-04-30

    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.

  17. Optimal split ratio in fractional-slot interior permanent magnet machines with non-overlapping windings

    Microsoft Academic Search

    L. J. Wu; Z. Q. Zhu; J. T. Chen; Z. P. Xia; G. W. Jewell

    2009-01-01

    The split ratio has been optimized for the maximum torque density when the airgap flux density is fixed in existing papers. However, the airgap flux density can vary with the split ratio significantly in interior permanent magnet (IPM) machines due to flux focusing. Therefore, an optimal airgap flux density may exist, together with the optimal split ratio, for the maximum

  18. A remote and sensorless stator winding thermal protection scheme for line-connected AC machines

    Microsoft Academic Search

    Sang Bin Lee; Thomas G. Habetler

    2002-01-01

    An advanced remote and sensorless thermal protection technique for line-connected AC machines is proposed in this paper. The proposed technique includes an algorithm for detecting abnormal cooling conditions due to reduced motor cooling ability in addition to a stator resistance (Rs)-based stator temperature (Ts) estimation scheme. The motor cooling ability monitoring algorithm can be implemented using the Rs estimates of

  19. A doubly-fed induction machine and energy storage system for wind power generation

    Microsoft Academic Search

    Chad Abbey; G. Joos

    2004-01-01

    Wind power has become a very important source of renewable energy, and has been shown to complement central generation effectively. However, good power quality from distributed generators is vital, and hence independent control of the real and reactive power is desirable. Also, there has been an increasing demand for alternative energy sources to behave like conventional generators, whereby their output

  20. 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...

  1. 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...

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

    Microsoft Academic Search

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

    1997-01-01

    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

  3. Calculation of ventilation for winded electric machines using three-dimensional numerical simulation of airflow current

    Microsoft Academic Search

    M. S. Dragomirov; A. M. Zaitsev; O. V. Kruglikov

    2008-01-01

    FlowVision software is employed to calculate the capacity and demand of built-in fans for electric motors produced by the\\u000a VEMZ public corporation. Experience in such usage is summarized. The results obtained can be used for the modification of\\u000a existing empirical methods of calculations for built-in fans in electric machines. The technique of making computational experiments\\u000a using FlowVision software is developed.

  4. Capturing energy from the wind

    SciTech Connect

    Schefter, J.L.

    1982-01-01

    The history of the harnessing of wind power and basic facts about the wind and wind machines are discussed. The small machines, the large turbines, and the direction for the future are described. (MHR)

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  6. 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)

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

    2014-05-01

    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.

  7. Dynamic supercoiling bifurcations of growing elastic filaments

    E-print Network

    Charles W. Wolgemuth; Raymond E. Goldstein; Thomas R. Powers

    2003-12-21

    Certain bacteria form filamentous colonies when the cells fail to separate after dividing. In Bacillus subtilis, Bacillus thermus, and cyanobacteria, the filaments can wrap into complex supercoiled structures as the cells grow. The structures may be solenoids or plectonemes, with or without branches in the latter case. Any microscopic theory of these morphological instabilities must address the nature of pattern selection in the presence of growth, for growth renders the problem nonautonomous and the bifurcations dynamic. To gain insight into these phenomena, we formulate a general theory for growing elastic filaments with bending and twisting resistance in a viscous medium, and study an illustrative model problem: a growing filament with preferred twist, closed into a loop. Growth depletes the twist, inducing a twist strain. The closure of the loop prevents the filament from unwinding back to the preferred twist; instead, twist relaxation is accomplished by the formation of supercoils. Growth also produces viscous stresses on the filament which even in the absence of twist produce buckling instabilities. Our linear stability analysis and numerical studies reveal two dynamic regimes. For small intrinsic twist the instability is akin to Euler buckling, leading to solenoidal structures, while for large twist it is like the classic writhing of a twisted filament, producing plectonemic windings. This model may apply to situations in which supercoils form only, or more readily, when axial rotation of filaments is blocked. Applications to specific biological systems are proposed.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  9. Lens Intermediate Filaments

    PubMed Central

    2009-01-01

    The ocular lens assembles two separate Intermediate Filament systems sequentially with differentiation. Canonical 8–11 nm IFs composed of Vimentin are assembled in lens epithelial cells and younger fiber cells, while the fiber cell-specific Beaded Filaments are switched on as fiber cell elongation initiates. Some of the key features of both filament systems are reviewed. PMID:19071112

  10. SRM filament wound case resin characterization studies

    NASA Technical Reports Server (NTRS)

    Chou, L. W.

    1985-01-01

    The amine cured epoxy wet winding resin used in fabrication of the SRM filament wound case is analyzed. High pressure liquid chromatography (HPSC) is utilized extensively to study lot-to-lot variation in both resin and curing agent. The validity of quantitative hplc methodology currently under development in-process resin/catalyst assay is assessed.

  11. Proceedings of the 2008 International Conference on Electrical Machines Paper ID 1434 DFIG-Based Wind Turbine Fault Diagnosis

    E-print Network

    Boyer, Edmond

    -Based Wind Turbine Fault Diagnosis Using a Specific Discrete Wavelet Transform E. Al-Ahmar1,2 , M for electrical and mechanical fault diagnosis in a DFIG-based wind turbine. The investigated technique unambiguously diagnose faults under transient conditions. Index Terms--Wind turbine, Doubly-Fed Induction

  12. Special issue on filamentation

    NASA Astrophysics Data System (ADS)

    Li, Ruxin; Milchberg, Howard; Mysyrowicz, André

    2014-05-01

    Journal of Physics B: Atomic, Molecular and Optical Physics is delighted to announce a forthcoming special issue on filamentation, to appear in the spring of 2015, and invites you to submit a paper. This special issue will attempt to give an overview of the present status of this field in order to create synergies and foster future developments. The issue is open to papers on the following issues: Theoretical advances on filamentation. Self-focusing and collapse. Filamentation in various media. Pulse self-compression and ultrafast processes in filaments. Molecular alignment and rotation. Filamentation tailoring. Interaction between filaments. Filament weather and pollution control. Filament induced condensation and precipitation. Terahertz science with filaments. Lasing in filaments. Filament induced molecular excitation and reaction. Electric discharge and plasma. Cross-disciplinary applications. Novel concepts related to these topics are particularly welcome. Please submit your article by 1 October 2014 (expected web publication: spring 2015) using our website http://mc04.manuscriptcentral.com/jphysb-iop. Submissions received after this date will be considered for the journal, but may not be included in the special issue. The issue will be edited by Ruxin Li, Howard Milchberg and André Mysyrowicz.

  13. Insulation failure detection in the stator windings of ASD-driven induction machines using standard deviation of line currents

    Microsoft Academic Search

    M. Alex Cash; Thomas G. Habetler

    1998-01-01

    This paper develops a straightforward, current-based scheme to detect stator turn faults that have occurred due to insulation failure in an ASD-driven, three-phase induction machine. The method employs simple statistical analysis to detect turn shorts in the stator of the machine. It is shown that the standard deviation of the calibrated, RMS line currents reveals a change in the machine's

  14. Externally refuelled optical filaments

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  15. Elasticity of biopolymer filaments.

    PubMed

    Holzapfel, Gerhard A; Ogden, Ray W

    2013-07-01

    Within the general one-dimensional theory of nonlinear elasticity we analyze the elasticity of biopolymer filaments. The approach adopted is purely mechanical but is reconciled with statistical physics approaches and allows for a proper formulation of boundary-value problems. By specializing the general framework we obtain force-extension relations for inextensible filaments and show how previous work on the biophysics of filaments fits within the framework. On the other hand, within the same framework, the theory of extensible filaments, which is appropriate for semi-flexible filaments such as F-actin, enables us to fit representative F-actin data. The specific formulas derived are relatively simple and the parameters involved have direct mechanical interpretations and are immediately related to the filament properties, including the initial end-to-end length, contour length and persistence length. PMID:23501788

  16. Are the filaments real?

    NASA Astrophysics Data System (ADS)

    Bhavsar, Suketu P.; Ling, E. Nigel

    1988-08-01

    The extent to which two selection effects, visual bias and random accidents, enter into the perception of filaments in the CfA catalog is investigated. The minimal spanning tree (MST) algorithm is used to identify the filaments, and a data-permuting technique is used to determine their statistical significance. The suitability of the MST for this purpose is demonstrated. It is found that the filaments are not accidental alignments or illusions; they disappear when the small-amplitude correlations at large scale lengths are removed. This is the first objective, statistical evidence for the physical existence of the filaments.

  17. Silicon carbide filaments - Microstructure

    NASA Technical Reports Server (NTRS)

    Nutt, S. R.; Wawner, F. E.

    1985-01-01

    The microstructure of chemically vapor deposited silicon carbide filaments has been examined using transmission electron microscopy. The filament bulk consisted of heavily faulted columnar subgrains of beta-SiC which were preferentially oriented such that 1 1 1 planes were parallel to the surface of the carbon fiber substrate. The protective coating on the filament surface was characterized by several microstructurally distinct layers, all of which consisted primarily of carbon. The first layers of the coating contained small crystallites of SiC in addition to turbostratic carbon, while the outer layers showed no evidence of SiC. Implications of the filament microstructure with respect to mechanical properties are discussed.

  18. Comparison of 5th order and 3rd order machine models for doubly fed induction generator (DFIG) wind turbines

    Microsoft Academic Search

    J. B. Ekanayake; L. Holdsworth; N. Jenkins

    2003-01-01

    With increasing concern over climate change, a number of countries have implemented new renewable energy targets, which require significant amounts of wind generation. It is now recognized that much of this new wind generation plant will be variable speed type using doubly fed induction generators (DFIG). In order to investigate the impacts of these DFIG installations on the operation and

  19. Filament proteins/A0292

    NSDL National Science Digital Library

    2009-04-14

    Cytoplasmic intermediate filaments (IF), also known as A0292, can be divided into 5 subclasses based on their biochemical properties, immunologic specificity and tissue distribution: keratin filaments in epithelial cells, vimentin filaments in cells ...

  20. Multiple coupled circuit modeling of induction machines

    Microsoft Academic Search

    Xiaogang Luo; Yuefeng Liao; H. A. Toliyat; A. El-Antably; T.A. Lipo

    1995-01-01

    A new multiple coupled circuit model is presented for simulation of induction machines with both arbitrary winding layout and\\/or unbalanced operating conditions. The model is derived by means of winding functions. No symmetry is assumed. The parameters of the model are calculated directly from the geometry and winding layout of the machine. The behavior of an induction machine during starting

  1. Kansas wind energy handbook

    SciTech Connect

    Not Available

    1981-01-01

    After a brief history of Kansas wind machines and definitions, wind machines are described and wind analysis and site evaluation are presented. This information is then related to energy output. Machine selection, economic evaluation, installation and operation are covered. Appended are an annotated bibliography, lists of wind machine suppliers and Kansas dealers, information about tax incentives, and worksheets. The wind information and analysis presented is of broad interest; the wind machine information is limited to those devices whose output is electricity. Only relatively small machines are covered. Calculations are presented in a non-technical manner, and in some cases, two methods of making calculations are given, one less technical than the other. (LEW)

  2. Structural design criteria for filament-wound composite shells

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  3. Compressive testing of filament-wound cylinders

    NASA Technical Reports Server (NTRS)

    Jensen, David W.; Hipp, Patrick A.

    1991-01-01

    An experimental investigation has been conducted on the compressive buckling and failure of filament-wound circular cylinders. This investigation identifies one of the relationships between structural performance and scale, as well as some of the causes of reduced structural performance in large-scale structures. It is hypothesized that this effect is related to two conditions: first, the number of fiber tow undulations; and second, the percentage of weak interfaces within the structure. The effect of winding pattern and the resulting location of the fiber undulations were studied by varying the winding parameters. Three types of cylinders were manufactured from Amoco T650-35/1908 graphite/epoxy preimpregnated tow with different winding sequences (0/+/-60)s, (+/-30/90)s, and (90/+/-30)s. The (90/+/-30)s cylinders were manufactured with two different winding patterns (distributed and classical) and radius-to-thickness ratios (15 and 55). All cylinders were loaded in compression to failure. Comparisons of the compressive strength and failure modes demonstrate the relationship between the winding parameters, scale, and structural performance of filament-wound composite cylinders.

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

    Microsoft Academic Search

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

    2008-01-01

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

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

    Microsoft Academic Search

    Chia-Chou Yehl; G. Y. Sizov; A. Sayed-Ahmed; N. A. O. Demerdash; R. J. Povinelli; E. E. Yaz; D. M. Ionel

    2007-01-01

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

  6. Optimal Split Ratio in Fractional-Slot Interior Permanent-Magnet Machines With Non-Overlapping Windings

    Microsoft Academic Search

    L. J. Wu; Z. Q. Zhu; J. T. Chen; Z. P. Xia; Geraint W. Jewell

    2010-01-01

    The split ratio has been optimized for the maximum torque density when the air-gap flux density is fixed in existing papers. However, the air-gap flux density can vary with the split ratio significantly in interior permanent-magnet (IPM) machines due to flux focusing. Therefore, an optimal air-gap flux density may exist, together with the optimal split ratio, for the maximum torque

  7. Millikelvin Lab Machine Shop

    E-print Network

    McQuade, D. Tyler

    Millikelvin Lab OP105­112 Machine Shop OP132 Resistive Magnet Shop CICC Winding Area Transformers Transformers Part Shop OP128 Dock Control Room 45 T Physical Plant Helium Recovery System MagnetCells Shipping This building is home to the Millikelvin lab, the control room, the resistive magnet and machine shops, the CICC

  8. Preflare heating of filaments

    SciTech Connect

    Malherbe, J.M.; Simon, G.; Mein, P.; Mein, N.; Schmieder, B.; Vial, J.C.

    1982-01-01

    The disappearance of a filament in connection with a flare and the reappearance of the filament at the same place after the flare which occurred twice during the FBS program on June 22, 1980 (S07, W13) (flare at 13.04 U.T.) and September 5, 1980 (flare at 7.52 U.T.) were investigated. The observations were obtained in the H-alpha line with the Multichannel Subtractive Double Pass Spectrograph operating at the solar tower in the Meudon Observatory, France. Results show that the disappearances begin a few minutes before the H-alpha impulsive phase and they are characterized by low velocities starting a few minutes before the flare outburst. The filaments reappear during the post-flare phase, which indicates a disappearance by heating mechanisms. Upwards motions occur in several points, without significantly disturbing preexisting downflows.

  9. Lightning Protection for Rotating Machines

    Microsoft Academic Search

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

    1944-01-01

    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

  10. Three fundamental cytoskeletal filaments Actin Microtubules (MT) Intermediate Filaments (IF)

    E-print Network

    Sniadecki, Nathan J.

    Session 4 #12;2 Three fundamental cytoskeletal filaments Actin Microtubules (MT) Intermediate;14 #12;15 Intermediate filaments (blue), plectin (green), Microtubules (red), anti-plectin labelled gold caps filament plus ends Latrunculin binds subunits and prevents their polymerization MICROTUBULE

  11. ORIGIN OF THE DENSE CORE MASS FUNCTION IN CONTRACTING FILAMENTS

    SciTech Connect

    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

    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.

  12. Solid friction between soft filaments

    NASA Astrophysics Data System (ADS)

    Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; Welch, David; Lau, A. W. C.; Vitelli, Vincenzo; Mahadevan, L.; Dogic, Zvonimir

    2015-06-01

    Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments’ overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes’s drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament’s elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.

  13. Reversibility of laser filamentation

    E-print Network

    Nicolas Berti; Wahb Ettoumi; Jérôme Kasparian; Jean-Pierre Wolf

    2014-09-03

    We investigate the reversibility of laser filamentation, a self-sustained, non-linear propagation regime including dissipation and time-retarded effects. We show that even losses related to ionization marginally affect the possibility of reverse propagating ultrashort pulses back to the initial conditions, although they make it prone to finite-distance blow-up susceptible to prevent backward propagation.

  14. Power from the Wind

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2004-01-01

    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,…

  15. A Review of Modern Wind Turbine Technology

    Microsoft Academic Search

    M. Balat

    2009-01-01

    This article deals with a review of modern wind turbine technology. Wind energy for electricity production today is a mature, competitive, and virtually pollution-free technology widely used in many areas of the world. Wind technology converts the energy available in wind to electricity or mechanical power through the use of wind turbines. A wind turbine is a machine for converting

  16. Filament heater current modulation for increased filament lifetime

    SciTech Connect

    Paul, J.D.; Williams, H.E. III

    1996-06-01

    The surface conversion H-minus ion source employs two 60 mil tungsten filaments which are approximately 17 centimeters in length. These filaments are heated to approximately 2,800 degrees centigrade by 95--100 amperes of DC heater current. The arc is struck at a 120 hertz rate, for 800 microseconds and is generally run at 30 amperes peak current. Although sputtering is considered a contributing factor in the demise of the filament, evaporation is of greater concern. If the peak arc current can be maintained with less average heater current, the filament evaporation rate for this arc current will diminish. In the vacuum of an ion source, the authors expect the filaments to retain much of their heat throughout a 1 millisecond (12% duty) loss of heater current. A circuit to eliminate 100 ampere heater currents from filaments during the arc pulse was developed. The magnetic field due to the 100 ampere current tends to hold electrons to the filament, decreasing the arc current. By eliminating this magnetic field, the arc should be more efficient, allowing the filaments to run at a lower average heater current. This should extend the filament lifetime. The circuit development and preliminary filament results are discussed.

  17. Wind energy utilization: A bibliography

    NASA Technical Reports Server (NTRS)

    1975-01-01

    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.

  18. Electromagnetic and Mechanical design of a Fractional-slot-windings Axial-flux PM synchronous machine with Soft Magnetic Compound Stator

    Microsoft Academic Search

    Fabrizio Marignetti; Giovanni Tomassi; Piergiacomo Cancelliere; Vincenzo Delli Colli; Roberto Di Stefano; Maurizio Scarano

    2006-01-01

    Despite their favorable aspect ratio, axial flux PM synchronous machines can compete with traditional radial flux machines in terms of torque and power density only if the number of pole-pairs is sufficiently high and the ratio axial length\\/outer diameter is low. Since axial flux PM synchronous machines have an inner stator hole, the number of stator slots is bounded, therefore

  19. CYTOPLASMIC FILAMENTS OF AMOEBA PROTEUS

    PubMed Central

    Pollard, Thomas D.; Ito, Susumu

    1970-01-01

    The role of filaments in consistency changes and movement in a motile cytoplasmic extract of Amoeba proteus was investigated by correlating light and electron microscopic observations with viscosity measurements. The extract is prepared by the method of Thompson and Wolpert (1963). At 0°C, this extract is nonmotile and similar in structure to ameba cytoplasm, consisting of groundplasm, vesicles, mitochondria, and a few 160 A filaments. The extract undergoes striking ATP-stimulated streaming when warmed to 22°C. Two phases of movement are distinguished. During the first phase, the apparent viscosity usually increases and numerous 50–70 A filaments appear in samples of the extract prepared for electron microscopy, suggesting that the increase in viscosity in caused, at least in part, by the formation of these thin filaments. During this initial phase of ATP-stimulated movement, these thin filaments are not detectable by phase-contrast or polarization microscopy, but later, in the second phase of movement, 70 A filaments aggregate to form birefringent microscopic fibrils. A preparation of pure groundplasm with no 160 A filaments or membranous organelles exhibits little or no ATP-stimulated movement, but 50–70 A filaments form and aggregate into birefringent fibrils. This observation and the structural relationship of the 70 A and the 160 A filaments in the motile extract suggest that both types of filaments may be required for movement. These two types of filaments, 50–70 A and 160 A, are also present in the cytoplasm of intact amebas. Fixed cells could not be used to study the distribution of these filaments during natural ameboid movement because of difficulties in preserving the normal structure of the ameba during preparation for electron microscopy. PMID:4915451

  20. Filament depolymerization by motor molecules

    E-print Network

    Gernot A. Klein; Karsten Kruse; Gianaurelio Cuniberti; Frank Juelicher

    2005-01-24

    Motor proteins that specifically interact with the ends of cytoskeletal filaments can induce filament depolymerization. A phenomenological description of this process is presented. We show that under certain conditions motors dynamically accumulate at the filament ends. We compare simulations of two microscopic models to the phenomenological description. The depolymerization rate can exhibit maxima and dynamic instabilities as a function of the bulk motor density for processive depolymerization. We discuss our results in relation to experimental studies of Kin-13 family motor proteins.

  1. Breakup of Liquid Filaments

    E-print Network

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

    2012-01-01

    in the formation of droplets from a thin water stream trickling from a tap, and in the quite different behaviour of the more viscous threads of honey or syrup flowing from a spoon [1]. The break- up of liquid jets is important in several practical con- texts... , including the dispersion of liquid drugs into res- pirable droplets, microfluidics, crop- and paint-spraying, and ink-jet printing [2–4]. There are also biological sys- tems in which either long filaments remain intact, or many droplets are formed [5, 6...

  2. Quantification of Processing Effects on Filament Wound Pressure Vessels. Revision

    NASA Technical Reports Server (NTRS)

    Aiello, Robert A.; Chamis, Christos C.

    2002-01-01

    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.

  3. Simple Machines

    NSDL National Science Digital Library

    Mr. Oldroyd

    2007-09-26

    Online Simple Machines Assignment OBJECTIVES: Student\\'s will be able to name and describe all seven simple machines. Students will be able to identify simple machines that they use everyday. Example: Clock = Gear INSTRUCTIONS: 1. Click on the Simple Machines Glossary page and familiarize yourself with the seven simple machines. Simple Machines Glossary Page 2. Students are to click on ...

  4. FILAMENT LENGTHS IN STRIATED MUSCLE

    Microsoft Academic Search

    SALLY G. PAGE; H. E. HUXLEY

    1963-01-01

    Filament lengths in resting and excited frog muscles have been measured in the electron microscope, and investigations made of the changes in length that are found under different conditions, to distinguish between those changes which arise during preparation and the actual differences in the living muscles. It is concluded that all the measured differences in filament length are caused by

  5. Solid friction between soft filaments

    PubMed Central

    Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; Welch, David; Lau, A.W. C.; Vitelli, Vincenzo; Mahadevan, L.; Dogic, Zvonimir

    2015-01-01

    Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments1,2. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments’ overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes’s drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament’s elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials. PMID:25730393

  6. Bacterial Filament Systems: Toward Understanding Their Emergent Behavior and Cellular Functions.

    PubMed

    Eun, Ye-Jin; Kapoor, Mrinal; Hussain, Saman; Garner, Ethan C

    2015-07-10

    Bacteria use homologs of eukaryotic cytoskeletal filaments to conduct many different tasks, controlling cell shape, division, and DNA segregation. These filaments, combined with factors that regulate their polymerization, create emergent self-organizing machines. Here, we summarize the current understanding of the assembly of these polymers and their spatial regulation by accessory factors, framing them in the context of being dynamical systems. We highlight how comparing the in vivo dynamics of the filaments with those measured in vitro has provided insight into the regulation, emergent behavior, and cellular functions of these polymeric systems. PMID:25957405

  7. The wind program in a typhoon environment

    Microsoft Academic Search

    Y. S. Tsao

    1981-01-01

    The present wind program in the Republic of China (including Taiwan and the off-shore islands under ROC control) is discussed. The collection of wind data in hopeful windmill sites, especially those on offshore islands and coastal areas is discussed. The installation of experimental small wind machines in the above-mentioned sites is described. For example, some small machines will be set

  8. Scales and properties of cold filaments in the southern Benguela upwelling system

    NASA Astrophysics Data System (ADS)

    Hösen, Elisabeth; Möller, Judith; Jochumsen, Kerstin; Quadfasel, Detlef

    2015-04-01

    The Benguela upwelling system is one of the four most active upwelling systems in the world. Meso-scale and submeso-scale structures like eddies and filaments are build up, due to instabilities at the front between the cold upwelled water and the warm surface water offshore. The heat exchange across the front is carried out mainly by such structures, especially filaments due to their offshore extent. Therefore cold upwelling filaments play an important role in the heat budget of the south-east Atlantic. This study is focussed on the southern part of the Benguela upwelling system, especially on the upwelling cell off Lüderitz. We combine satellite data and ship-borne measurements to investigate the appearance of such filaments and their properties (vertical and horizontal extent, mean temperature anomaly, mean velocity etc.). We use infra-red measurements of the MODIS satellite from 2011 to 2014. Two cruises in the region of interest were carried out in August 2013 and February 2014 and provide highly resolved surface data of temperature and salinity as well as vertical information on temperature, salinity and velocity. The spatial and temporal distribution of the filaments including the meridional and longitudinal extent is determined using a frequency analysis (wavelet analysis) of our data sets. Most filaments occurred between 25°S and 27°S, corresponding to the position of the Lüderitz cell. The observed filaments have a meridional extent between 5km and 44km and propagate more than 20km offshore. The lifetime of a filament is between 2 and 12 days. The time series of satellite data provides information on the seasonal and year-to-year variability in the appearance of filaments. Additionally the variability of the forcing winds is analysed and results are connected to the appearance of filaments. The filament activity is highest in southern summer, corresponding to the main upwelling season. The ship-borne measurements allow a highly resolved analysis of the horizontal and vertical structures of the filaments. The vertical extent of the filaments is between 80m and 140m. Further we obtain from this analysis characteristic features in the distinct parts of a filament, e.g. centre and boundary region. The centre of a filament is characterised by a westward current, while the flow is eastward in the boundary region. In contrast to most previous studies, which are often case studies of one or two filaments, we are able to look at more than 150 filaments per year due to the combination of ship-borne and satellite measurements.

  9. Purification of native myosin filaments from muscle.

    PubMed Central

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

    2001-01-01

    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

  10. Simple Machines

    NSDL National Science Digital Library

    AWOL

    2006-11-15

    This activity is designed to learn about simple machines and to have fun doing so! First, use this website to learn backround information on the basics of simple machines. Try the quiz! Simple Machines Learning Site Next, play a game that tests your ability to identify simple machines.... Edheads: Simple Machines Finally, view this video to see how students your age used applied simple machines to do a cool task... Building Simple Machines: A Glass of Milk, Please ...

  11. Comparative Biomechanics of Thick Filaments and Thin Filaments with Functional Consequences for Muscle Contraction

    PubMed Central

    Miller, Mark S.; Tanner, Bertrand C. W.; Nyland, Lori R.; Vigoreaux, Jim O.

    2010-01-01

    The scaffold of striated muscle is predominantly comprised of myosin and actin polymers known as thick filaments and thin filaments, respectively. The roles these filaments play in muscle contraction are well known, but the extent to which variations in filament mechanical properties influence muscle function is not fully understood. Here we review information on the material properties of thick filaments, thin filaments, and their primary constituents; we also discuss ways in which mechanical properties of filaments impact muscle performance. PMID:20625489

  12. The Bearingless Electrical Machine

    NASA Technical Reports Server (NTRS)

    Bichsel, J.

    1992-01-01

    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.

  13. Quiet-Region Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Choudhary, Debi Prasad; Moore, Ronald L.

    2004-01-01

    We report characteristics of quiescent filament eruptions that did not produce coronal mass ejections (CMEs). It is known that there is a dichotomy of quiescent filament eruptions: those that produce CMEs and those that do not. We examined the quiescent filament eruptions, each of which was located far from disk center (greater than or equal to 0.7 R(sub Sun)) in diffuse remnant magnetic fields of decayed active regions, was well observed in Ha observations and Fe XII, and had good coronagraph coverage. We present the similarity and differences of two classes of filament eruptions. From their lack of CME production and the appearance of their eruptive motion in Fe XII movies, we conclude that the non-CME-producing filament eruptions are confined eruptions like the confined filament eruptions in active regions. We take the similarity of the confined and eruptive quiescent filament eruptions with their active-region counterparts to favor runaway tether-cutting connection for unleashing the magnetic explosion in all these eruptions.

  14. Fixed pitch wind turbines

    Microsoft Academic Search

    D. B. Fenn; L. A. Viterna

    1978-01-01

    Wind turbines designed for fixed pitch operation offer potential reductions in the cost of the machine by eliminating many costly components. It was shown that a rotor can be designed which produces the same energy annually as Mod-0 but which regulates its power automatically by progressively stalling the blades as wind speed increases. Effects of blade twist, taper, root cutout,

  15. Wind Energy Systems.

    ERIC Educational Resources Information Center

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

    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…

  16. The sedimentation of flexible filaments

    E-print Network

    Lei Li; Harishankar Manikantan; David Saintillan; Saverio E. Spagnolie

    2013-06-19

    The dynamics of a flexible filament sedimenting in a viscous fluid are explored analytically and numerically. Compared to the well-studied case of sedimenting rigid rods, the introduction of filament compliance is shown to cause a significant alteration in the long-time sedimentation orientation and filament geometry. A model is developed by balancing viscous, elastic, and gravitational forces in a slender-body theory for zero-Reynolds-number flows, and the filament dynamics are characterized by a dimensionless elasto-gravitation number. Filaments of both non-uniform and uniform cross-sectional thickness are considered. In the weakly flexible regime, a multiple-scale asymptotic expansion is used to obtain expressions for filament translations, rotations, and shapes. These are shown to match excellently with full numerical simulations. Furthermore, we show that trajectories of sedimenting flexible filaments, unlike their rigid counterparts, are restricted to a cloud whose envelope is determined by the elasto-gravitation number. In the highly flexible regime we show that a filament sedimenting along its long axis is susceptible to a buckling instability. A linear stability analysis provides a dispersion relation, illustrating clearly the competing effects of the compressive stress and the restoring elastic force in the buckling process. The instability travels as a wave along the filament opposite the direction of gravity as it grows and the predicted growth rates are shown to compare favorably with numerical simulations. The linear eigenmodes of the governing equation are also studied, which agree well with the finite-amplitude buckled shapes arising in simulations.

  17. Beam profile analysis for the C&MS B231 electron beam welding machines

    Microsoft Academic Search

    J. W. Elmer; A. T. Teruya; M. Gauthier

    1997-01-01

    The electron beams produced by two different welders were examined using computer assisted tomographic (CT) analysis. The machines used are Hamilton Standard welders with 150 kV\\/50mA maximum. One machine uses a ribbon filament while the other uses a hairpin filament. The objective of this study was to characterize the beam power distribution on each machine to see if weld parameters

  18. Dynamic Fluctuations of Semiflexible Filaments

    NASA Astrophysics Data System (ADS)

    Everaers, R.; Jülicher, F.; Ajdari, A.; Maggs, A. C.

    1999-05-01

    We study both the longitudinal and transverse fluctuations of a semiflexible filament. Using scaling arguments and numerical simulations, we find several regimes for the longitudinal fluctuations which, for short times, scale as ~t7/8 and are correlated over a length l2~t1/8. Our results are pertinent to experiments on cross-linked filament systems and motor-filament assays. The techniques we develop for the analysis of dynamic correlations should have wide applications in the study of polymer systems.

  19. Torque Angle Loop Analysis of Synchronous Machines

    Microsoft Academic Search

    A. S. Gopala Rao; D. Thukaram; B. S. Ramakrishna Iyengar

    1986-01-01

    This paper reports the dynamic stability analysis of a single machine infinite bus system through torque angle loop analysis and forms an extension of the work on Block diagrams and torque angle loop analysis of synchronous machines reported by I. Nagy [3]. It aims to incorporate in the machine model, the damper windings (one on each axis) and to compare

  20. New Measurement of Synchronous Machine Quantities

    Microsoft Academic Search

    Hiroshi Kaminosono; Kiyotaka Uyeda

    1968-01-01

    Synchronous machine quantities are used in the various studies of power system behavior under both normal and abnormal conditions. Instead of the IEEE test code 115 [1] generally employed, this paper describes two approaches to measure synchronous machine quantities of each winding with the machine at standstill, namely, the indicial response method and the low-requency response method. These quantities are

  1. Characteristics of wind turbine generators for wind power plants

    Microsoft Academic Search

    E. H. Camm; M. R. Behnke; O. Bolado; M. Bollen; M. Bradt; C. Brooks; W. Dilling; M. Edds; W. J. Hejdak; D. Houseman; S. Klein; F. Li; J. Li; P. Maibach; T. Nicolai; J. Patino; S. V. Pasupulati; N. Samaan; S. Saylors; T. Siebert; T. Smith; M. Starke; R. Walling

    2009-01-01

    This paper presents a summary of the most important characteristics of wind turbine generators applied in modern wind power plants. Various wind turbine generator designs, based on classification by machine type and speed control capabilities, are discussed along with their operational characteristics, voltage, reactive power, or power factor control capabilities, voltage ride-through characteristics, behavior during short circuits, and reactive power

  2. Predicting Noise From Wind Turbines

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1990-01-01

    Computer program WINDY predicts broadband noise spectra of horizontal-axis wind-turbine generators. Enables adequate assessment of impact of broadband wind-turbine noise. Effects of turbulence, trailing-edge wakes, and bluntness taken into account. Program has practical application in design and siting of wind-turbine machines acceptable to community. Written in GW-Basic.

  3. Leonid meteoroids from different filaments

    NASA Astrophysics Data System (ADS)

    Koten, P.

    2012-01-01

    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.

  4. Secondary ELM Filaments in NSTX

    SciTech Connect

    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

    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.

  5. Electron emitting filaments for electron discharge devices

    DOEpatents

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

    1983-06-10

    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.

  6. Electron emitting filaments for electron discharge devices

    DOEpatents

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

    1988-01-01

    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.

  7. Intermediate filaments in nervous tissues

    Microsoft Academic Search

    RONALD K. H. LIEM; SHU-HUI YEN; GARY D. SALOMON; MICHAEL L. SHELANSKI

    1978-01-01

    Intermediate filaments have been isolated from rabbit intradural spinal nerve roots by the axonal flotation method. This method was modified to avoid exposure of axons to low ionic strength medium. The purified filaments are morphologically 75-80% pure. The gel electrophoretogr am shows four major bands migrating at 200,000, 145,000, 68,000, and 60,000 daltons, respectively. A similar preparation from rabbit brain

  8. Galaxy filaments as pearl necklaces

    NASA Astrophysics Data System (ADS)

    Tempel, E.; Kipper, R.; Saar, E.; Bussov, M.; Hektor, A.; Pelt, J.

    2014-12-01

    Context. Galaxies in the Universe form chains (filaments) that connect groups and clusters of galaxies. The filamentary network includes nearly half of the galaxies and is visually the most striking feature in cosmological maps. Aims: We study the distribution of galaxies along the filamentary network, trying to find specific patterns and regularities. Methods: Galaxy filaments are defined by the Bisous model, a marked point process with interactions. We use the two-point correlation function and the Rayleigh Z-squared statistic to study how galaxies and galaxy groups are distributed along the filaments. Results: We show that galaxies and groups are not uniformly distributed along filaments, but tend to form a regular pattern. The characteristic length of the pattern is around 7 h-1 Mpc. A slightly smaller characteristic length 4 h-1 Mpc can also be found, using the Z-squared statistic. Conclusions: We find that galaxy filaments in the Universe are like pearl necklaces, where the pearls are galaxy groups distributed more or less regularly along the filaments. We propose that this well-defined characteristic scale could be used to test various cosmological models and to probe environmental effects on the formation and evolution of galaxies. Appendices are available in electronic form at http://www.aanda.org

  9. A confined flare above filaments

    NASA Astrophysics Data System (ADS)

    Dalmasse, K.; Chandra, R.; Schmieder, B.; Aulanier, G.

    2014-01-01

    We present the dynamics of two filaments and a C-class flare observed in NOAA 11589 on 2012 October 16. We used the multi-wavelength high-resolution data from SDO, as well as THEMIS and ARIES ground-based observations. The observations show that the filaments are progressively converging towards each other without merging. We find that the filaments have opposite chirality which may have prevented them from merging. On October 16, a C3.3 class flare occurred without the eruption of the filaments. According to the standard solar flare model, after the reconnection, post-flare loops form below the erupting filaments whether the eruption fails or not. However, the observations show the formation of post-flare loops above the filaments, which is not consistent with the standard flare model. We analyze the topology of the active region's magnetic field by computing the quasi-separatrix layers (QSLs) using a linear force-free field extrapolation. We find a good agreement between the photospheric footprints of the QSLs and the flare ribbons. We discuss how slipping or slip-running reconnection at the QSLs may explain the observed dynamics.

  10. Vertical-axis wind-turbine program

    SciTech Connect

    Braasch, R.H.

    1981-01-01

    During the interval since the Fourth Biennial Wind Energy Conference, the vertical axis wind turbine program has experienced significant progress. The purpose of this paper is to review that progress in aerodynamics research, structural dynamics research, and machine development.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  12. Wind power and other energy options

    Microsoft Academic Search

    Inglis

    1979-01-01

    Past experience with wind power is considered along with the mechanics of wind energy conversion, small wind-power installations, large wind-power machines and installations, other solar-related energy sources, geophysical energy sources, nuclear power from fission, nuclear power from fusion, a comparison of dollar costs of wind power and nuclear power, social costs of wind power and nuclear power, and the choice

  13. Wind power and other energy options

    Microsoft Academic Search

    D. R. Inglis

    1978-01-01

    Past experience with wind power is considered along with the mechanics of wind energy conversion, small wind-power installations, large wind-power machines and installations, other solar-related energy sources, geophysical energy sources, nuclear power from fission, nuclear power from fusion, a comparison of dollar costs of wind power and nuclear power, social costs of wind power and nuclear power, and the choice

  14. Machine Learning

    Microsoft Academic Search

    Xin Yao; Yong Liu

    Machine learning is a very active sub-field of artificial intelligence concerned with the development of computational models\\u000a of learning. Machine learning is inspired by the work in several disciplines: cognitive sciences, computer science, statistics,\\u000a computational complexity, information theory, control theory, philosophy, and biology. Simply speaking, machine learning is\\u000a learning by machine. From a computational point of view, machine learning refers

  15. Filament-induced ultrafast birefringence in gases

    NASA Astrophysics Data System (ADS)

    Yuan, S.; Li, M.; Feng, Y.; Li, H.; Zheng, L.; Chin, S. L.; Zeng, H.

    2015-05-01

    Femtosecond laser filaments generated by ultrashort laser pulses induce a remarkable birefringence over the whole filament length. Any linearly polarized femtosecond laser pulse probing this filament will be decomposed into two orthogonal polarization components propagating at different speeds resulting in an elliptical polarization. The latter in turn reflects the birefringence inside the filament zone. The filament-induced birefringence could be due to instantaneous electronic or delayed molecular response depending on different types of gases. In this paper, we review recent progress on filament-induced ultrafast birefringence in gases.

  16. The influence of Filaments in the Private Flux Region on Divertor Power and Particle Deposition

    NASA Astrophysics Data System (ADS)

    Harrison, James

    2014-10-01

    Recent advances in imaging of the MAST divertor have revealed, for the first time, evidence for filaments in the private flux region (PFR). Detailed analysis of the image data shows 3 distinct types of fluctuations occurring within the divertor volume: highly sheared filaments in the SOL originating from the outer midplane, high frequency (>50 kHz) filaments near the separatrix of the outer divertor leg and filaments in the private flux region originating from inner divertor leg. With the need to extrapolate divertor performance from existing machines to future devices, these observations can contribute to our quantitative understanding of transport in the PFR. In particular, they suggest that transport in the PFR is, at least in part, driven by turbulence, which may not be well captured by the Eich/Wagner description of the divertor footprint, expressed in terms of exponential decay in space above the X-point and Gaussian spreading below the X-point. The PFR filaments are observed to move largely parallel with the flux surfaces in a way equivalent to a toroidal angular velocity of order 2 ×104 rad/s in H-mode, and slower by a factor of order 2 in L-mode. During their transit parallel to the flux surfaces across the PFR, the filaments eject plasma in bursts, away from the separatrix, deeper into the private flux region. Correlation analysis suggests that they are generated by processes local to the inner divertor leg, as there is a weak correlation between fluctuations in the SOL and PFR above what is expected from line integration effects. Scaling of filament properties with machine operating parameters, such as plasma current, density and auxiliary heating power will be presented, together with a comparison with data from divertor Langmuir probes and IR thermography to estimate the role PFR filaments play in determining the width of the divertor footprint.

  17. Development of Nylon Based FDM Filament for Rapid Tooling Application

    NASA Astrophysics Data System (ADS)

    Singh, R.; Singh, S.

    2014-04-01

    There has been critical need for development of cost effective nylon based wire to be used as feed stock filament for fused deposition modelling (FDM) machine. But hitherto, very less work has been reported for development of alternate solution of acrylonitrile butadiene styrene (ABS) based wire which is presently used in most of FDM machines. The present research work is focused on development of nylon based wire as an alternative of ABS wire (which is to be used as feedstock filament on FDM) without changing any hardware or software of machine. For the present study aluminium oxide (Al2O3) as additive in different proportion has been used with nylon fibre. Single screw extruder was used for wire preparation and wire thus produced was tested on FDM. Mechanical properties i.e. tensile strength and percentage elongation of finally developed wire have been optimized by Taguchi L9 technique. The work represented major development in reducing cost and time in rapid tooling applications.

  18. Nonequilibrium transport in superconducting filaments

    NASA Technical Reports Server (NTRS)

    Arutyunov, K. YU.; Danilova, N. P.; Nikolaeva, A. A.

    1995-01-01

    The step-like current-voltage characteristics of highly homogeneous single-crystalline tin and indium thin filaments has been measured. The length of the samples L approximately 1 cm was much greater than the nonequilibrium quasiparticle relaxation length Lambda. It was found that the activation of a successive i-th voltage step occurs at current significantly greater than the one derived with the assumption that the phase slip centers are weakly interacting on a scale L much greater than Lambda. The observation of 'subharmonic' fine structure on the voltage-current characteristics of tin filaments confirms the hypothesis of the long-range phase slip centers interaction.

  19. The M-band: an elastic web that crosslinks thick filaments in the center of the sarcomere

    Microsoft Academic Search

    Irina Agarkova; Jean-Claude Perriard

    2005-01-01

    The sarcomere of striated muscle is an efficient molecular machine, characterized by perfect structural organization of contractile filaments. This order is ensured by the sarcomere cytoskeleton, an important element of which is the M-band, believed to maintain the thick filament lattice. We review here recent progress in understanding the M-band function and its structural organization. We explain how the M-band

  20. Numerical simulation of vortex breakdown by the vortex-filament method

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  1. Adjustable speed generators for wind turbines based on doubly-fed induction machines and 4-quadrant IGBT converters linked to the rotor

    Microsoft Academic Search

    S. Muller; M. Deicke; Rik W. De Doncker

    2000-01-01

    Wind turbines are being built at power levels above 1.5 MW. Higher power levels are being anticipated for offshore applications. To limit mechanical stresses and power surges in these high power systems, speed control is necessary. The doubly-fed induction generator (DFIG) system is investigated as a viable alternative to adjust speed over a wide range while keeping the cost of

  2. Studies on the dynamics of limited filaments

    E-print Network

    Bonde, Jeffrey David

    2010-01-01

    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 ...

  3. Simple Machines

    NSDL National Science Digital Library

    At this website, EdHeads, a nonprofit, offers five interactive, animated modules to educate second- through sixth-graders about simple machines. By identifying the many machines located throughout a house, students can learn about fulcrums, wheel and axles, levers, pulleys, inclined planes, and much more. The website is equipped with simple animations to help children understand how the machines work. After students have a handle on simple machines, they can begin to see how they work together to create compound machines. The website also provides a brief glossary summarizing nine types of simple machines. This site is also reviewed in the February 18, 2005_NSDL Physical Sciences Report_.

  4. A Three-Dimensional Magnetohydrodynamic Model of Planetary Nebula Jets, Knots, and Filaments

    E-print Network

    K. H. Tsui

    2008-03-31

    The morphologies of planetary nebulae are believed to be self-organized configurations. These configurations are modeled by three-dimensional temporally self-similar magnetohydrodynamic solutions with radial flow, under the gravitational field of a central star of mass $M$. These solutions reproduce basic features, such as jets, point-symmetric knots, and filaments, through plasma pressure, mass density, and magnetic field lines. The time evolution function of the radial velocity starts as a slow wind and terminates as a fast wind.

  5. Orthotropic photoelastic analysis of residual stresses in filament-wound rings

    Microsoft Academic Search

    C. E. Knight

    1972-01-01

    In the filament-winding process for fabricating composite materials, winding tension and other factors combine to produce\\u000a a residual-stress state in the wound structure. Techniques have been developed for producing a transparent composite, and\\u000a the orthotropic photoelastic method was applied to determine this residual stress in circumferentially wound rings.\\u000a \\u000a Results from the photoelastic analysis were compared with two other residual-stress-determination methods:

  6. Driven Transport on open filaments with inter-filament switching processes

    E-print Network

    Subhadip Ghosh; Ignacio Pagonabarraga; Sudipto Muhuri

    2015-07-12

    We study a two filament driven lattice gas model with oppositely directed species of particles moving on two parallel filaments with filament switching processes and particle inflow and outflow at filament ends. The filament switching process is {\\it correlated} such that particles switch filaments with finite probability only when oppositely directed particles meet on the same filament. This model mimics some of the coarse grained features observed in context of microtubule (MT) based intracellular transport, wherein cellular cargo loaded and off-loaded at filament ends are transported on multiple parallel microtubule (MT) filaments and can switch between the parallel microtubule filaments. We focus on a regime where the filaments are weakly coupled, such that filament switching rates scale inversely as the length of the filament. We find that the interplay (off)loading processes at the boundaries and the filament switching process leads to some distinctive features of the system. These features includes occurrence of variety of phases in the system with inhomogeneous density profiles including localized density shocks, density difference across the filaments and bidirectional current flows in the system. We analyze the system by developing a mean field (MF) theory and comparing the results obtained from the MF theory with the Monte Carlo (MC) simulations of the dynamics of the system. We find that the steady state density and current profiles of particles and the phase diagram obtained within the MF picture matches quite well with MC simulation results. These findings maybe useful for studying multi-filament intracellular transport.

  7. Solar Filaments and Photospheric Network

    Microsoft Academic Search

    Yong Lin; Jun Elin Wiik; Oddbjørn Engvold; Luc Rouppe Van Der Voort; Zoe A. Frank

    2005-01-01

    The locations of barbs of quiescent solar filaments are compared with the photospheric\\/chromospheric network, which thereby serves as a proxy of regions with enhanced concentrations of magnetic flux. The study covers quiet regions, where also the photospheric network as represented by flow converging regions, i.e., supergranular cell boundaries, contain largely weak magnetic fields. It is shown that close to 65%

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

    E-print Network

    Peskin, Charles S.

    on the separation distance between the two filaments. Our simulation results agree with that of the experiment two orders of magnitude lower than that of the experiment. © 2003 American Institute of Physics. DOI the two-dimensional analog of a flag flapping in the wind has much to teach us about biological swimming2

  9. Performance of outside filament-wound hybrid FRP-concrete beams

    Microsoft Academic Search

    Anup Chakrabortty; Amar Khennane; Obada Kayali; Evgeny Morozov

    2011-01-01

    A novel configuration of a hybrid FRP-concrete beam is presented. The beam consists of a GFRP pultruded profile, a CFRP laminate, and a concrete block all wrapped up using filament winding. Three different concrete blocks were used: high strength concrete, normal strength concrete and steel fibres reinforced high strength concrete. The major feature of the design is that it does

  10. Composite rotor blades for wind turbine generators

    Microsoft Academic Search

    W. D. Weigel

    1981-01-01

    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

  11. SIMPLE MACHINES

    NSDL National Science Digital Library

    Mrs. MacHose

    2007-03-10

    You will be learning about several types of simple machines. Have fun!! Review the first website (which is right here!! Simple machines) . It has information about simple machines. DON\\"T click until you read all directions!!! Prepare to discuss each type in class. You will need to take some basic notes about each machine, using a bubble-map format. Don\\'t forget ...

  12. Sewing Machines!!

    NSDL National Science Digital Library

    Miss. Walker

    2008-10-20

    Learn the Parts of a Sewing Machine This should help you understand the history of sewing machines and how they work. For this assignment, answer these questions on a sheet of paper and bring it to class. Click on this link to go to a site which will briefly explain the history of the sewing machine: wikipedia Was ...

  13. 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.

  14. Electrostatic Machines

    NSDL National Science Digital Library

    De Queiroz, Antonio Carlos M.

    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.

  15. Beam profile analysis for the C{ampersand}MS B231 electron beam welding machines

    SciTech Connect

    Elmer, J. W.; Teruya, A.T.; Gauthier, M.

    1997-06-12

    The electron beams produced by two different welders were examined using computer assisted tomographic (CT) analysis. The machines used are Hamilton Standard welders with 150 kV/50mA maximum. One machine uses a ribbon filament while the other uses a hairpin filament. The objective of this study was to characterize the beam power distribution on each machine to see if weld parameters could easily be transferred between machines. Beam focus, voltage, and current settings were pre-selected to duplicate the welding conditions used in LLNL program applications. The results show that the actual beam currents measured by Faraday cup are 5 to 10% higher for the first machine and 30% lower for the second. The CT analysis of the beam shapes shows that the hairpin filament welder produces an elliptical beam shape in the sharp focus condition that defocuses to a diamond shape. The ribbon filament welder produced less of an elliptical beam shape in the sharp focus condition, but when defocused, acquires an elliptical shape. CT analysis of the effects of defocus on the peak power density shows that the hairpin filament drops in peak power density much more quickly than the ribbon filament for a given amount of defocus. Furthermore, it was more difficult to find and repeat the sharp focus condition for the hairpin filament, particularly at higher beam currents.

  16. Fixed pitch wind turbines

    NASA Technical Reports Server (NTRS)

    Fenn, D. B.; Viterna, L. A.

    1978-01-01

    Wind turbines designed for fixed pitch operation offer potential reductions in the cost of the machine by eliminating many costly components. It was shown that a rotor can be designed which produces the same energy annually as Mod-0 but which regulates its power automatically by progressively stalling the blades as wind speed increases. Effects of blade twist, taper, root cutout, and airfoil shape on performance are discussed as well as various starting technqiues.

  17. Wind Energy Conversion Using A Self-Excited Induction Generator

    Microsoft Academic Search

    G. Raina; O. P. Malik

    1983-01-01

    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

  18. Transformation of wing boundary layer in the filament wake

    NASA Astrophysics Data System (ADS)

    Mikhaelis, M. V.; Zanin, B. Yu.; Katasonov, M. M.

    2014-12-01

    Results of an experimental study of the air flow past a straight-wing model in a low-turbulence wind tunnel are reported. The influence of a turbulent wake due to a thin filament on the structure of boundary layer on the model surface was examined. Flow visualization in boundary layer, hot-wire measurements of flow velocity, and also measurements of the amplitude and frequency spectra of flow pulsations, were performed. The wake substantially modified the boundary layer flow pattern: the separation bubble disappeared from the flow, and the formation of longitudinal structures was observed.

  19. PARTIAL SLINGSHOT RECONNECTION BETWEEN TWO FILAMENTS

    SciTech Connect

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

    2013-02-10

    We present a rare observation of an interaction between two filaments around AR 11358 and AR 11361 on 2011 December 3 that is strongly suggestive of the occurrence of slingshot reconnection. A small elbow-shaped active-region filament (F12) underwent a failed eruption that brought it into contact with a nearby larger, thicker filament (F34). Accompanied by the appearance of complicated internal structures below the erupting F12, its two legs separated away from each other and then connected into F34. This process led the filaments to change their connectivity to form two newly linked filaments, and one of them showed a clear inverse {gamma}-shape. However, the alteration in the filament connectivity was imperfect since F34 is discernible after the eruption. These observations can be interpreted as a partial slingshot reconnection between two filaments that had unequal axial magnetic flux.

  20. Partial Slingshot Reconnection between Two Filaments

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    We present a rare observation of an interaction between two filaments around AR 11358 and AR 11361 on 2011 December 3 that is strongly suggestive of the occurrence of slingshot reconnection. A small elbow-shaped active-region filament (F12) underwent a failed eruption that brought it into contact with a nearby larger, thicker filament (F34). Accompanied by the appearance of complicated internal structures below the erupting F12, its two legs separated away from each other and then connected into F34. This process led the filaments to change their connectivity to form two newly linked filaments, and one of them showed a clear inverse ?-shape. However, the alteration in the filament connectivity was imperfect since F34 is discernible after the eruption. These observations can be interpreted as a partial slingshot reconnection between two filaments that had unequal axial magnetic flux.

  1. Wind commercialization and Alcoa Vertical Axis Wind Turbines

    Microsoft Academic Search

    P. N. Vosburgh

    1979-01-01

    Five basic Darrieus-type Vertical Axis Wind Turbines which feature a troposkein shaped rotor blade are described along with the operation of several research machines including one of 17 m (60 kW) height and 61 cm chord blades that has demonstrated a performance coefficient of 42%. Some of the advantages of the design are the utilization of winds from all directions,

  2. WIND ENERGY Wind Energ. 2013; 16:7790

    E-print Network

    Papalambros, Panos

    . The machine has the capability to be attached to an offshore wind turbine support structure, where it can of a computational model for design analysis of a novel marine turbine Turaj Ashuri1 , Gerard van Bussel1 and Stefan be achieved by using the existing knowledge and experience from offshore and wind energy industry

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

  4. Putnam's power from the wind

    SciTech Connect

    Koeppl, G.W.

    1982-01-01

    The construction of a megawatt-scale wind turbine is traced from the turbine's development, fabrication and erection until the program's termination in 1945. Current government efforts to commercialize wind power are discussed. National wind energy assessments are included, as are preliminary assessments of wind generation capacity. Characteristics of wind resources and methods for selecting wind turbine sites are described. Coverage includes the application of a simple model based on the analysis of the Smith-Putnam wind data of the 1940's, ecological indicators of wind energy, and numerical and physical modes of wind-flow over different terrains. Current design and development projects to develop large-scale wind machines are explained. Legal, institutional and environmental issues are evaluated. Discussions are featured on the Public Utility Regulatory Policies Act, safety, electromagnetic interference, noise, ecological effects, aesthetics and land use. Also investigated are positive impacts such as net energy return and the displacement of the environmental impacts of other technologies. An examination of the economics of wind generation focuses on machine size optimization trends, busbar energy costs, and utility production model assessments of the value of wind generation. (LEW)

  5. Magnetoelastic coupling in rotating electrical machines

    Microsoft Academic Search

    Anouar Belahcen

    2005-01-01

    This paper presents a method for the calculation of vibrations in rotating electrical machines when the magnetoelastic coupling is to be taken into account. A dynamic model for the magnetoelastic coupling is presented, where the circuit equations for windings of the machine are also coupled with the magnetic field. Calculation results for coupled and uncoupled cases are compared. It is

  6. Performance analysis of asynchronized synchronous machine

    Microsoft Academic Search

    B. W. HOGG; M. RAMA MURTHI

    1973-01-01

    An asynchronized synchronous machine has two field windings and two special excitation control systems. The paper examines the performance of this type of machine during both synchronous and asynchronous operating conditions. The results illustrate the effects of subsidiary feedback signals in the control loops on equilibrium conditions and stability. They are supported by analysis, which establishes the conditions for stability

  7. A Novel High Power Density Segmented Switched Reluctance Machine

    Microsoft Academic Search

    R. Vandana; Naresh Vattikuti; B. G. Fernandes

    2008-01-01

    In switched reluctance machine (SRM), the power density can be increased by using full pitched winding instead of concentrated winding. It is reported that full pitched segmented switched reluctance machine (SSRM) can give 40% higher torque than conventional SRM for the same frame size. In this paper, it is shown that SSRM can give approximately double the torque for the

  8. Filament wound rocket motor chambers

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The design, analysis, fabrication and testing of a Kevlar-49/HBRF-55A filament wound chamber is reported. The chamber was fabricated and successfully tested to 80% of the design burst pressure. Results of the data reduction and analysis from the hydrotest indicate that the chamber design and fabrication techniques used for the chamber were adequate and the chamber should perform adequately in a static test.

  9. Generalization of Filament Braiding Model for Amyloid Fibril Assembly

    NASA Astrophysics Data System (ADS)

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

    2001-03-01

    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.

  10. Impact of submesoscale processes on dynamics of phytoplankton filaments

    NASA Astrophysics Data System (ADS)

    Shulman, Igor; Penta, Bradley; Richman, James; Jacobs, Gregg; Anderson, Stephanie; Sakalaukus, Peter

    2015-03-01

    In Monterey Bay, CA, during northwesterly, upwelling favorable winds, the development of a southward flowing cold jet along the entrance to the Bay is often observed. This dense cold jet separates warm waters of the anticyclonic circulation offshore from the water masses inside the Bay. Interactions between the cold jet and the offshore anticyclonic circulation generate ageostrophic secondary circulation (ASC) cells due to submesoscale processes as, for example, flow interaction with the development of surface frontogenesis and nonlinear Ekman pumping. Based on observations and modeling studies, we evaluate the impact of these submesoscale processes on the formation of chlorophyll a filaments during late spring-earlier summer, and late summer time frames. We show that during the late summer time frame, ASC leads to the development of filaments with high values of chlorophyll a concentration along the edge of the cold jet-in contrast to the earlier summer time, when the ASC mixes phytoplankton much deeper to the area below of the euphotic depth, and chlorophyll a filaments are 3-4 times weaker.

  11. Diagnosis of femtosecond plasma filament by channeling microwaves along the filament

    SciTech Connect

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

    2013-05-20

    We introduce a simple, fast, and non-intrusive experimental method to obtain the basic parameters of femtosecond laser-generated plasma filament. The method is based on the channeling of microwaves along both a plasma filament and a well-defined conducting wire. By comparing the detected microwaves that propagate along the plasma filament and a copper wire with known conductivity and spatial dimension, the basic parameters of the plasma filament can be easily obtained. As a result of the possibility of channeling microwave radiation along the plasma filament, we were then able to obtain the plasma density distribution along the filament length.

  12. Analysis of flexural rigidity of actin filaments propelled by surface adsorbed myosin motors

    PubMed Central

    Bengtsson, Elina; Persson, Malin; Månsson, Alf

    2013-01-01

    Actin filaments are central components of the cytoskeleton and the contractile machinery of muscle. The filaments are known to exist in a range of conformational states presumably with different flexural rigidity and thereby different persistence lengths. Our results analyze the approaches proposed previously to measure the persistence length from the statistics of the winding paths of actin filaments that are propelled by surface-adsorbed myosin motor fragments in the in vitro motility assay. Our results suggest that the persistence length of heavy meromyosin propelled actin filaments can be estimated with high accuracy and reproducibility using this approach provided that: (1) the in vitro motility assay experiments are designed to prevent bias in filament sliding directions, (2) at least 200 independent filament paths are studied, (3) the ratio between the sliding distance between measurements and the camera pixel-size is between 4 and 12, (4) the sliding distances between measurements is less than 50% of the expected persistence length, and (5) an appropriate cut-off value is chosen to exclude abrupt large angular changes in sliding direction that are complications, e.g., due to the presence of rigor heads. If the above precautions are taken the described method should be a useful routine part of in vitro motility assays thus expanding the amount of information to be gained from these. © 2013 Wiley Periodicals, Inc. PMID:24039103

  13. Mechanical properties of branched actin filaments

    NASA Astrophysics Data System (ADS)

    Razbin, Mohammadhosein; Falcke, Martin; Benetatos, Panayotis; Zippelius, Annette

    2015-07-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force–extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measured in lamellipodia. These networks reproduce both the weak and strong force response of lamellipodia as measured in force–velocity experiments. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament depends on the orientation distribution of the filaments. The ratio exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about two and essentially independent from network compression, graft elasticity and filament persistence length.

  14. Dynamics of Contracting Asymmetric Viscoelastic Filaments

    NASA Astrophysics Data System (ADS)

    Anthony, Christopher; Thete, Sumeet; Appathurai, Santosh; Bhat, Pradeep; Basaran, Osman; Harris, Michael

    2013-11-01

    In ink-jet printing and atomization, slender filaments are routinely formed. Such filaments either contract to form a single drop or breakup into multiple drops, e.g. by end pinching. Beginning with papers by Schulkes (1996) and Notz & Basaran (2004), past studies have focused exclusively on the contraction dynamics of Newtonian filaments. Also in these studies, initial filament shapes are taken to be long cylinders terminated by two identical spherical caps (symmetric filaments). In emerging applications, e.g. ink-jet printing of complex fluids, the filaments are viscoelastic (VE) fluids. Moreover, older experiments by Notz et al. (2001) and more recent ones by Castrejón-Pita et al. (2012) show that initial filament shapes resemble long, tapered cylinders terminated by hemispherical caps of unequal radii (asymmetric filaments). Therefore, we analyze the contraction dynamics of both asymmetric and symmetric filaments of VE fluids using the Giesekus model. Rather than solving the full set of equations governing the problem, we take advantage of filament slenderness and solve a much simpler set of 1D equations (Eggers, 1997). We then use a finite element method with Streamline Upwind/Petrov Galerkin (SUPG) formulation (Brooks & Hughes, 1982) to solve the reduced equations.

  15. Mechanical properties of branched actin filaments.

    PubMed

    Razbin, Mohammadhosein; Falcke, Martin; Benetatos, Panayotis; Zippelius, Annette

    2015-01-01

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measured in lamellipodia. These networks reproduce both the weak and strong force response of lamellipodia as measured in force-velocity experiments. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament depends on the orientation distribution of the filaments. The ratio exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about two and essentially independent from network compression, graft elasticity and filament persistence length. PMID:26040560

  16. Hydrophobic loop dynamics and actin filament stability.

    PubMed

    Scoville, Damon; Stamm, John D; Toledo-Warshaviak, Dora; Altenbach, Christian; Phillips, Martin; Shvetsov, Alexander; Rubenstein, Peter A; Hubbell, Wayne L; Reisler, Emil

    2006-11-14

    It has been postulated that the hydrophobic loop of actin (residues 262-274) swings out and inserts into the opposite strand in the filament, stabilizing the filament structure. Here, we analyzed the hydrophobic loop dynamics utilizing four mutants that have cysteine residues introduced at a single location along the yeast actin loop. Lateral, copper-catalyzed disulfide cross-linking of the mutant cysteine residues to the native C374 in the neighboring strand within the filament was fastest for S265C, followed by V266C, L267C, and then L269C. Site-directed spin labeling (SDSL) studies revealed that C265 lies closest to C374 within the filament, followed by C266, C267, and then C269. These results are not predicted by the Holmes extended loop model of F-actin. Furthermore, we find that disulfide cross-linking destroys L267C and L269C filaments; only small filaments are observed via electron microscopy. Conversely, phalloidin protects the L267C and L269C filaments and inhibits their disulfide cross-linking. Combined, our data indicate that, in solution, the loop resides predominantly in a "parked" position within the filament but is able to dynamically populate other conformational states which stabilize or destabilize the filament. Such states may be exploited within a cell by filament-stabilizing and -destabilizing factors. PMID:17087511

  17. Mechanical properties of branched actin filaments

    E-print Network

    Mohammadhosein Razbin; Martin Falcke; Panayotis Benetatos; Annette Zippelius

    2015-06-26

    Cells moving on a two dimensional substrate generate motion by polymerizing actin filament networks inside a flat membrane protrusion. New filaments are generated by branching off existing ones, giving rise to branched network structures. We investigate the force-extension relation of branched filaments, grafted on an elastic structure at one end and pushing with the free ends against the leading edge cell membrane. Single filaments are modeled as worm-like chains, whose thermal bending fluctuations are restricted by the leading edge cell membrane, resulting in an effective force. Branching can increase the stiffness considerably; however the effect depends on branch point position and filament orientation, being most pronounced for intermediate tilt angles and intermediate branch point positions. We describe filament networks without cross-linkers to focus on the effect of branching. We use randomly positioned branch points, as generated in the process of treadmilling, and orientation distributions as measured in lamellipodia. These networks reproduce both the weak and strong force response of lamellipodia as measured in force-velocity experiments. We compare properties of branched and unbranched networks. The ratio of the network average of the force per branched filament to the average force per unbranched filament depends on the orientation distribution of the filaments. The ratio exhibits compression dependence and may go up to about 4.5 in networks with a narrow orientation distribution. With orientation distributions measured in lamellipodia, it is about two and essentially independent from network compression, graft elasticity and filament persistence length.

  18. Feasibility of utilizing wind energy in Thailand

    Microsoft Academic Search

    Jamkrajang

    1984-01-01

    The purpose of this study was to ascertain the feasibility of utilizing wind energy to meet part of the energy demands related to pumping water and to generating electricity for the rural households in Thailand. The data for this study were divided into three different areas: (1) wind speed data, (2) the wind machine performance data, and (3) the rural

  19. Rotating electric machine with fluid supported parts

    DOEpatents

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

    1981-01-01

    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.

  20. Machine Learning

    Microsoft Academic Search

    Crina Grosan; Ajith Abraham

    \\u000a Machine Learning[6][8][12] is concerned with the study of building computer programs that automatically improve and\\/or adapt\\u000a their performance through experience. Machine learning can be thought of as “programming by example” [11]. Machine learning\\u000a has many common things with other domains such as statistics and probability theory (understanding the phenomena that have\\u000a generated the data), data mining (finding patterns in the

  1. Nonlinear theory of kinetic Alfven waves propagation and multiple filament formation

    SciTech Connect

    Sharma, R. P.; Malik, M.; Singh, H. D. [Centre for Energy Studies, Indian Institute of Technology Delhi, 110016 (India)

    2008-06-15

    In this paper, the filamentation of kinetic Alfven waves (KAWs) has been studied by assuming that the incident Gaussian beam of KAWs may not remain Gaussian during the filament formation. The solution of the nonlinear dynamical equation of KAWs has been obtained by developing the semi-analytical approach in solar wind plasma. Magnetic field structures of the KAW have been presented in x-z plane. The analytical theory using eikonal approximation has been used beyond the paraxial domain. The effect on spectral index of the turbulence has also been studied.

  2. Partial Eruption of a Filament with Twisting Non-uniform Fields

    NASA Astrophysics Data System (ADS)

    Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Xiang, Yongyuan; Cai, Yunfang; Liu, Weiwei

    2015-05-01

    The eruption of a filament in a kinklike fashion is often regarded as a signature of kink instability. However, the kink instability threshold for the filament’s magnetic structure is not widely understood. Using H? observations from the New Vacuum Solar Telescope, we present a partial eruptive filament. During the eruption, the filament thread appeared to split from its middle and to break out in a kinklike fashion. In this period, the remaining filament material stayed below and erupted without the kinking motion later on. The coronal magnetic field lines associated with the filament are obtained from nonlinear force-free field extrapolations using the twelve-minute-cadence vector magnetograms of the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory. We studied the extrapolated field lines passing through the magnetic dips which are in good agreement with the observed filament. The field lines are non-uniformly twisted and appear to be composed of two twisted flux ropes winding around each other. One of them has a higher twist than the other, and the flux rope with the higher twist has its dips aligned with the kinking eruptive thread at the beginning of its eruption. Before the eruption, moreover, the flux rope with the higher twist was found to expand with an approximately constant field twist. In addition, the helicity flux maps deduced from the HMI magnetograms show that some helicity is injected into the overlying magnetic arcade, but no significant helicity is injected into the flux ropes. Accordingly, we suggest that the highly twisted flux rope became kink unstable when the instability threshold declined with the expansion of the flux rope.

  3. Femtosecond Laser Filamentation for Atmospheric Sensing

    PubMed Central

    Xu, Huai Liang; Chin, See Leang

    2011-01-01

    Powerful femtosecond laser pulses propagating in transparent materials result in the formation of self-guided structures called filaments. Such filamentation in air can be controlled to occur at a distance as far as a few kilometers, making it ideally suited for remote sensing of pollutants in the atmosphere. On the one hand, the high intensity inside the filaments can induce the fragmentation of all matters in the path of filaments, resulting in the emission of characteristic fluorescence spectra (fingerprints) from the excited fragments, which can be used for the identification of various substances including chemical and biological species. On the other hand, along with the femtosecond laser filamentation, white-light supercontinuum emission in the infrared to UV range is generated, which can be used as an ideal light source for absorption Lidar. In this paper, we present an overview of recent progress concerning remote sensing of the atmosphere using femtosecond laser filamentation. PMID:22346566

  4. Analogue Gravity and ultrashort laser pulse filamentation

    E-print Network

    D. Faccio; S. Cacciatori; V. Gorini; V. G. Sala; A. Averchi; A. Lotti; M. Kolesik; J. V. Moloney

    2009-09-18

    Ultrashort laser pulse filaments in dispersive nonlinear Kerr media induce a moving refractive index perturbation which modifies the space-time geometry as seen by co-propagating light rays. We study the analogue geometry induced by the filament and show that one of the most evident features of filamentation, namely conical emission, may be precisely reconstructed from the geodesics. We highlight the existence of favorable conditions for the study of analogue black hole kinematics and Hawking type radiation.

  5. Precision Machining

    NSDL National Science Digital Library

    Leske, Cavin.

    Basic machining processes are introduced on a Web site that is devoted to engineering fundamentals (1). 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. An in-depth discussion of waterjet operation and applications is available from Southern Methodist University (2). Waterjets are often cited as being much more precise than traditional machining techniques. The Waterjet Video Vault (3) contains clips of waterjet machines in action. The video of the foam cutting procedure is especially interesting, as it shows how quick and accurate the machining process can be. An online guide to cross process machining, which incorporates elements from various conventional and unconventional techniques, is provided by the Mechanical Engineering Department at Columbia University (4). Some remarkable and innovative techniques that have surfaced over the past few years are outlined, including underwater laser machining and plasma-assisted machining. Entirely different and exotic machining techniques are required for creating microelectromechanical systems (MEMS) and other extremely small devices. The Caltech Micromachining Laboratory (5) maintains an archive of research highlights and papers on its homepage, including a paper on a MEMS-driven flapping wing for a palm-sized aerial vehicle. An online article from Modern Machine Shop (6) outlines some new technologies and research in the area of high speed machining. A particularly interesting section of the article describes a system developed at the University of Florida that aims to enable micromachining to achieve rotational speeds of standard machining processes, specifically up to a half million rotations per minute. Cutting edge waterjet innovations are the subject of a February 2003 feature from a publication of the Society of Manufacturing Engineers (7). Extremely high pressure nozzles are being developed to improve cutting speed, and enhanced software for controlling machine movements is also a focus of study. This news article (8) from June 20, 2003 describes an electrochemical machining process that is being used to fabricate complex nanostructures. The work, produced by German and U.S. researchers, has the potential to compete with current lithographic processes.

  6. Viscoelastic properties of vimentin compared with other filamentous biopolymer networks

    Microsoft Academic Search

    Paul A. Janmey; Ursula Euteneuer; Peter Traub; Manfred Schliwa

    1991-01-01

    The cytoplasm of vertebrate cells contains three distinct filamentous biopolymers, the microtu- bules, microfilaments, and intermediate filaments. The basic structural elements of these three filaments are linear polymers of the proteins tubulin, actin, and vimentin or another related intermediate filament pro- tein, respectively. The viscoelastic properties of cyto- plasmic filaments are likely to be relevant to their biologic function, because

  7. Harvesting the wind

    SciTech Connect

    Kahn, R.D.

    1984-11-01

    This paper describes the wind farms in the Altamont Pass, the Tehachapi Mountains, and the San Gorgonio pass, all in California. The threat by Congress to eliminate federal tax credits could put the fledgling industry in the doldrums. The author shows how the selection of the right wind site can make the difference between a profitable venture and an expensive kinetic sculpture. To improve reliability wind-farm developers have turned to more durable Danish turbines from Zond, Windmatic, and Bonus. Recent research under DOE sponsorship has studied large-scale MOD-2 machines built by Boeing, several of which are now operating at a PGandL site north of San Francisco. The result of recent new standards may require the filing of quarterly reports on machine capacity, performance, and the amounts of electricity produced from the installation.

  8. The Regulation of Filamentous Growth in Yeast

    PubMed Central

    Cullen, Paul J.; Sprague, George F.

    2012-01-01

    Filamentous growth is a nutrient-regulated growth response that occurs in many fungal species. In pathogens, filamentous growth is critical for host–cell attachment, invasion into tissues, and virulence. The budding yeast Saccharomyces cerevisiae undergoes filamentous growth, which provides a genetically tractable system to study the molecular basis of the response. Filamentous growth is regulated by evolutionarily conserved signaling pathways. One of these pathways is a mitogen activated protein kinase (MAPK) pathway. A remarkable feature of the filamentous growth MAPK pathway is that it is composed of factors that also function in other pathways. An intriguing challenge therefore has been to understand how pathways that share components establish and maintain their identity. Other canonical signaling pathways—rat sarcoma/protein kinase A (RAS/PKA), sucrose nonfermentable (SNF), and target of rapamycin (TOR)—also regulate filamentous growth, which raises the question of how signals from multiple pathways become integrated into a coordinated response. Together, these pathways regulate cell differentiation to the filamentous type, which is characterized by changes in cell adhesion, cell polarity, and cell shape. How these changes are accomplished is also discussed. High-throughput genomics approaches have recently uncovered new connections to filamentous growth regulation. These connections suggest that filamentous growth is a more complex and globally regulated behavior than is currently appreciated, which may help to pave the way for future investigations into this eukaryotic cell differentiation behavior. PMID:22219507

  9. Simulations of magnetic fields in filaments

    E-print Network

    M. Bruggen; M. Ruszkowski; A. Simionescu; M. Hoeft; C. Dalla Vecchia

    2005-08-10

    The intergalactic magnetic field within filaments should be less polluted by magnetised outflows from active galaxies than magnetic fields in clusters. Therefore, filaments may be a better laboratory to study magnetic field amplification by structure formation than galaxy clusters which typically host many more active galaxies. We present highly resolved cosmological AMR simulations of magnetic fields in the cosmos and make predictions about the evolution and structure of magnetic fields in filaments. Comparing our results to observational evidence for magnetic fields in filaments suggests that amplification of seed fields by gravitational collapse is not sufficient to produce IGM fields. Finally, implications for cosmic ray transport are discussed.

  10. Sensing combustion intermediates by femtosecond filament excitation.

    PubMed

    Li, He-Long; Xu, Huai-Liang; Yang, Bo-Si; Chen, Qi-Dai; Zhang, Tao; Sun, Hong-Bo

    2013-04-15

    Simultaneous monitoring of multiple combustion intermediates using femtosecond filament-induced nonlinear spectroscopy is demonstrated. Clean fluorescence emissions from free radicals CH, CN, NH, OH, and C(2), as well as atomic C and H, are observed when a femtosecond filament is formed in the laminar ethanol/air flame on an alcohol burner. The fluorescence signals of these species are found to vary as functions of the position of interaction of the filament with the flame along the vertical axis of the central combusting flow, opening up a possibility for remote combustion diagnostic in engines by the excitation of femtosecond laser filament. PMID:23595448

  11. Effect of Surface Roughness on Wind Turbine Performance 

    E-print Network

    Ehrmann, Robert Schaefer

    2014-06-25

    Wind farm operators observe production deficits as machines age. Quantifying deterioration on individual components is difficult, but one potential explanation is accumulation of blade surface roughness. Historically, wind turbine airfoils were...

  12. Effect of Surface Roughness on Wind Turbine Performance

    E-print Network

    Ehrmann, Robert Schaefer

    2014-06-25

    Wind farm operators observe production deficits as machines age. Quantifying deterioration on individual components is difficult, but one potential explanation is accumulation of blade surface roughness. Historically, wind turbine airfoils were...

  13. Maximum power tracking control scheme for wind generator systems

    E-print Network

    Mena, Hugo Eduardo

    2009-05-15

    solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier...

  14. Maximum power tracking control scheme for wind generator systems

    E-print Network

    Mena Lopez, Hugo Eduardo

    2008-10-10

    solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier...

  15. Simple Machines

    NSDL National Science Digital Library

    KET

    2010-11-16

    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.

  16. Excavating machines

    SciTech Connect

    Plummer, D.

    1980-10-21

    The excavating machine has a cutter carrying boom carried by a boom support member which can be swung about an axis extending in the direction of the roadway. The machine includes a cutter unit and a stay unit each of which is releasably anchorable in the roadway and each of which can be advanced relative to the other unit.

  17. Midterm periods of solar filaments

    NASA Astrophysics Data System (ADS)

    Zou, Peng; Li, Qixiu

    2014-12-01

    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.

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

    PubMed Central

    Das, Dipjyoti; Das, Dibyendu; Padinhateeri, Ranjith

    2014-01-01

    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

  19. Caldesmon and the structure of smooth muscle thin filaments: electron microscopy of isolated thin filaments

    Microsoft Academic Search

    Catherine Moody; William Lehman; Roger Craig

    1990-01-01

    Summary Native and synthetic vertebrate smooth muscle thin filaments have been examined by electron microscopy in order to determine the arrangement of the regulatory protein caldesmon. In synthetic filaments of actin—caldesmon, long slender molecules were sometimes seen running along the thin filament, suggesting that caldesmon can associate with actin along its length, while at other times lateral projections were observed.

  20. Microcyle conidiation in filamentous fungi.

    PubMed

    Jung, Boknam; Kim, Soyeon; Lee, Jungkwan

    2014-03-01

    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

  1. Microcyle Conidiation in Filamentous Fungi

    PubMed Central

    Jung, Boknam; Kim, Soyeon

    2014-01-01

    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

  2. Lamp automatically switches to new filament on burnout

    NASA Technical Reports Server (NTRS)

    Ingle, W. B.

    1966-01-01

    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.

  3. Identification of coronal holes and filament channels in SDO/AIA 193Å images via geometrical classification methods

    NASA Astrophysics Data System (ADS)

    Reiss, M.; Temmer, M.; Rotter, T.; Hofmeister, S. J.; Veronig, A. M.

    In this study, we describe and evaluate shape measures for distinguishing between coronal holes and filament channels as observed in Extreme Ultraviolet (EUV) images of the Sun. For a set of well-observed coronal hole and filament channel regions extracted from SDO/AIA 193Å images we analyze their intrinsic morphology during the period 2011 to 2013, by using well known shape measures from the literature and newly developed geometrical classification methods. The results suggest an asymmetry in the morphology of filament channels giving support for the sheared arcade or weakly twisted flux rope model for filaments. We find that the proposed shape descriptors have the potential to reduce coronal hole classification errors and are eligible for screening techniques in order to improve the forecasting of solar wind high-speed streams from CH observations in solar EUV images.

  4. Filament-induced electric events in thunderstorms

    Microsoft Academic Search

    J. Kasparian; R. Ackermann; Y.-B. André; G. Méchain; G. Méjean; B. Prade; P. Rohwetter; E. Salmon; L. A. Schlie; K. Stelmaszczyk; J. Yu; A. Mysyrowicz; R. Sauerbrey; L. Wöste; J.-P. Wolf

    2009-01-01

    Under conditions of high electric field during two thunderstorms, we observed a statistically significant number of electric events synchronized with the ionized filaments generated by ultrashort laser pulses in the atmosphere. This observation suggests that corona discharges have been triggered by filaments.

  5. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1998-04-01

    This invention relates to a process for making filaments of metal compounds and more particularly to a process for making silver metal filaments. The United States Government has rights to this invention pursuant to Contract No. DE-AC05-8421400 with Lockheed Martin Energy Systems, Inc. awarded by the US Department of Energy.

  6. Scaling laws for laser-induced filamentation

    NASA Astrophysics Data System (ADS)

    Zhokhov, P. A.; Zheltikov, A. M.

    2014-04-01

    Despite all the complexity of the underlying nonlinear physics, the filamentation of ultrashort optical field wave forms is shown to obey a set of physically transparent scaling laws. This scaling is applicable within a remarkably broad range of laser powers, pulse widths, gas pressures, and propagation paths, suggesting specific recipes for the power scaling of filamentation-based pulse compression.

  7. EXPERIMENTAL PROGRESS: CURRENT FILAMENTATION INSTABILITY STUDY *

    E-print Network

    Brookhaven National Laboratory

    of large magnetic fields and radiation. The generation of magnetic fields and radiation could possiblyEXPERIMENTAL PROGRESS: CURRENT FILAMENTATION INSTABILITY STUDY * Brian Allen , Patric Muggli, University of California at Los Angeles Los Angeles, CA 90095, USA Abstract Current Filamentation Instability

  8. A first approach to filament dynamics

    Microsoft Academic Search

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

    2010-01-01

    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

  9. Application of Gaussian Process to wind speed forecasting for wind power generation

    Microsoft Academic Search

    Hiroyuki Mori; Eitaro Kurata

    2008-01-01

    This paper proposes a new kernel machine method for short-term wind speed forecasting. Renewable energy is attractive to protect environment. As renewable energy, wind power generation, solar energy generation, geothermal energy generation, etc. are spread in the world. In Japan, wind power generation is of main concern due to the execution of the Renewable Portfolio Standard (RPS). However, it is

  10. Quantifying protein diffusion and capture on filaments

    E-print Network

    Emanuel Reithmann; Louis Reese; Erwin Frey

    2015-03-03

    The functional relevance of regulating proteins is often limited to specific binding sites such as the ends of microtubules or actin-filaments. A localization of proteins on these functional sites is of great importance. We present a quantitative theory for a diffusion and capture process, where proteins diffuse on a filament and stop diffusing when reaching the filament's end. It is found that end-association after one-dimensional diffusion is the main source for tip-localization of such proteins. As a consequence, diffusion and capture is highly efficient in enhancing the reaction velocity of enzymatic reactions, where proteins and filament ends are to each other as enzyme and substrate. We show that the reaction velocity can effectively be described within a Michaelis-Menten framework. Together one-dimensional diffusion and capture beats the (three-dimensional) Smoluchowski diffusion limit for the rate of protein association to filament ends.

  11. Microwave hybrid heating of alumina filaments

    SciTech Connect

    Vogt, G.J.; Unruh, W.P.

    1993-05-01

    Low loss oxide ceramics filaments are not readily heated to sintering temperatures (>900{degrees}C) by direct microwave heating at 2.45 GHz. Use of high power levels typically yields thermal runaway with catastrophic melting. In other studies, hybrid, or indirect, heating has been successfully applied to processing bulk oxide ceramics. In this work, commercial alumina-based filaments have been indirectly heated to 700{degrees}--900{degrees}C through a lossy carbon coating on the filament tow. Specific filaments can reach higher temperatures by direct coupling after preheating with a lossy coating. The results of microwave hybrid heating in a single mode TE{sub 102} cavity will be described for commercial alumina-based filaments.

  12. Microwave hybrid heating of alumina filaments

    SciTech Connect

    Vogt, G.J.; Unruh, W.P.

    1993-01-01

    Low loss oxide ceramics filaments are not readily heated to sintering temperatures (>900[degrees]C) by direct microwave heating at 2.45 GHz. Use of high power levels typically yields thermal runaway with catastrophic melting. In other studies, hybrid, or indirect, heating has been successfully applied to processing bulk oxide ceramics. In this work, commercial alumina-based filaments have been indirectly heated to 700[degrees]--900[degrees]C through a lossy carbon coating on the filament tow. Specific filaments can reach higher temperatures by direct coupling after preheating with a lossy coating. The results of microwave hybrid heating in a single mode TE[sub 102] cavity will be described for commercial alumina-based filaments.

  13. Generalized minimal principle for rotor filaments.

    PubMed

    Dierckx, Hans; Wellner, Marcel; Bernus, Olivier; Verschelde, Henri

    2015-05-01

    To a reaction-diffusion medium with an inhomogeneous anisotropic diffusion tensor D, we add a fourth spatial dimension such that the determinant of the diffusion tensor is constant in four dimensions. We propose a generalized minimal principle for rotor filaments, stating that the scroll wave filament strives to minimize its surface area in the higher-dimensional space. As a consequence, stationary scroll wave filaments in the original 3D medium are geodesic curves with respect to the metric tensor G=det(D)D^{-1}. The theory is confirmed by numerical simulations for positive and negative filament tension and a model with a non-stationary spiral core. We conclude that filaments in cardiac tissue with positive tension preferentially reside or anchor in regions where cardiac cells are less interconnected, such as portions of the cardiac wall with a large number of cleavage planes. PMID:25978269

  14. Extending optical filaments using auxiliary dress beams

    NASA Astrophysics Data System (ADS)

    Mills, Matthew; Heinrich, Matthias; Kolesik, Miroslav; Christodoulides, Demetrios

    2015-05-01

    Dressed optical filaments offer a way to greatly protract an optical filament’s natural length while at the same time mitigating nonlinear losses and unwanted multifilamentation effects. In this article, we first theoretically reexamine the quasi-linear propagation dynamics of a standard Gaussian-ring wavefront and then proceed to explore several optical dress beam arrangements of equal-energy. The purpose of this study is to numerically simulate configurations which more economically utilize the finite amount of energy available for filament prolongation. In general, we find that parameters such as beam width and inward radial chirp, when adjusted in unison, play an important role in extending a filament whereas the spatial distribution of power in the optical dress only affects the characteristic intensity fluctuations seen during refocusing cycles.

  15. Generalized Minimal Principle for Rotor Filaments

    NASA Astrophysics Data System (ADS)

    Dierckx, Hans; Wellner, Marcel; Bernus, Olivier; Verschelde, Henri

    2015-05-01

    To a reaction-diffusion medium with an inhomogeneous anisotropic diffusion tensor D , we add a fourth spatial dimension such that the determinant of the diffusion tensor is constant in four dimensions. We propose a generalized minimal principle for rotor filaments, stating that the scroll wave filament strives to minimize its surface area in the higher-dimensional space. As a consequence, stationary scroll wave filaments in the original 3D medium are geodesic curves with respect to the metric tensor G =det (D )D-1 . The theory is confirmed by numerical simulations for positive and negative filament tension and a model with a non-stationary spiral core. We conclude that filaments in cardiac tissue with positive tension preferentially reside or anchor in regions where cardiac cells are less interconnected, such as portions of the cardiac wall with a large number of cleavage planes.

  16. Unwinding Motion of a Twisted Active Region Filament

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  17. Filament Activation in Response to Magnetic Flux Emergence and Cancellation in Filament Channels

    NASA Astrophysics Data System (ADS)

    Li, Ting; Zhang, Jun; Ji, Haisheng

    2015-05-01

    We conducted a comparative analysis of two filaments that showed a quite different activation in response to the flux emergence within the filament channels. The observations from the Solar Dynamics Observatory (SDO) and Global Oscillation Network Group (GONG) were made to analyze the two filaments on 2013 August 17 - 20 (SOL2013-08-17) and September 29 (SOL2013-09-29). The first event showed that the main body of the filament was separated into two parts when an active region (AR) emerged with a maximum magnetic flux of about 6.4×1021 Mx underlying the filament. The close neighborhood and common direction of the bright threads in the filament and the open AR fan loops suggest a similar magnetic connectivity of these two flux systems. The equilibrium of the filament was not destroyed three days after the start of the emergence of the AR. To our knowledge, similar observations have never been reported before. In the second event, the emerging flux occurred nearby a barb of the filament with a maximum magnetic flux of 4.2×1020 Mx, about one order of magnitude lower than that of the first event. Two patches of parasitic polarity in the vicinity of the barb merged, then cancelled with nearby network fields. About 20 hours after the onset of the emergence, the filament erupted. Our findings imply that the location of emerging flux within the filament channel is probably crucial to filament evolution. If the flux emergence appears nearby the barbs, it is highly likely that the emerging flux and the filament magnetic fields will cancel, which may lead to the eruption of the filament. The comparison of the two events shows that the emergence of a small AR may still not be enough to disrupt the stability of a filament system, and the actual eruption only occurs after the flux cancellation sets in.

  18. The invertebrate myosin filament: subfilament arrangement of the solid filaments of insect flight muscles.

    PubMed Central

    Beinbrech, G; Ashton, F T; Pepe, F A

    1992-01-01

    Transverse sections (approximately 140 nm thick) of solid myosin filaments of the flight muscles of the fleshfly, Phormia terrae-novae, the honey bee, Apis mellifica, and the waterbug, Lethocerus uhleri, were photographed in a JEM model 200A electron microscope at 200 kV. The images were digitized and computer processed by rotational filtering. In each of these filaments it was found that the symmetry of the core and the wall was not the same. The power spectra of the images showed sixfold symmetry for the wall and threefold symmetry for the core of the filaments. The images of the filaments in each muscle were superimposed according to the sixfold center of the wall. These averaged images for all three muscles showed six pairs of subunits in the wall similar to those found in the wall of tubular filaments. From serial sections of the fleshfly filaments, we conclude that the subunits in the wall of the filaments represent subfilaments essentially parallel to the long axis of the filament. In each muscle there are additional subunits in the core, closely related to the subunits in the wall. Evaluation of serial sections through fleshfly filaments suggests that the relationship of the three subunits observed in the core to those in the wall varies along the length of the filaments. In waterbug filaments there are three dense and three less dense subunits for a total of six all closely related to the wall. Bee filaments have three subunits related to the wall and three subunits located eccentrically in the core of the filaments. The presence of core subunits can be related to the paramyosin content of the filaments. Images FIGURE 1 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 FIGURE 9 FIGURE 12 PMID:1617135

  19. Machine therapy

    E-print Network

    Dobson, Kelly E. (Kelly Elizabeth), 1970-

    2007-01-01

    Machine Therapy is a new practice combining art, design, psychoanalysis, and engineering work in ways that access and reveal the vital, though often unnoticed, relevance of people's interactions and relationships with ...

  20. 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.

  1. Simple Machines

    NSDL National Science Digital Library

    This series of three interactive, multimedia activities introduce and demonstrate the properties of six simple machines. Specifically, the lessons show how levers, pulleys, inclined planes, screws, wheels and axles, and wedges can reduce the amount of work done by humans. After learning about the characteristics of each classification, users can try to find the simple machines that make up a lawn mower. By inspecting the mower from different angles, several simple machines are revealed and must be identified. The final activity lets users test their knowledge of the mechanics of simple machines. Following a builder through each stage of constructing a tree house, users can apply equations to determine the mechanical advantage supplied by using the tools.

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

    E-print Network

    Ran, Li

    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 ...

  3. Monel Machining

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Castle Industries, Inc. is a small machine shop manufacturing replacement plumbing repair parts, such as faucet, tub and ballcock seats. Therese Castley, president of Castle decided to introduce Monel because it offered a chance to improve competitiveness and expand the product line. Before expanding, Castley sought NERAC assistance on Monel technology. NERAC (New England Research Application Center) provided an information package which proved very helpful. The NASA database was included in NERAC's search and yielded a wealth of information on machining Monel.

  4. Wind Turbine Acoustics

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    2009-01-01

    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.

  5. Ultrasonic analysis of Kevlar-epoxy filament wound spherical test specimens

    SciTech Connect

    Brosey, W.D.

    1984-12-06

    Increased use of composite materials in enclosed geometries such as cylindrical, spherical, or conical shapes has led to the desire to transfer and further develop the most promising nondestructive evaluation (NDE) techniques used on nonenclosed geometries to enclosed geometries. 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, and an alternate high void content winding pattern. Ultrasonic C-scan analysis of Kevlar-epoxy filament wound spheres was performed to determine detectability of normal winding patterns and implanted flaw conditions in the composite using this technique. Ultrasonic waveform analysis was performed in both the time and frequency domains to determine the detectability and locatability of structural flaws within the composite.

  6. Performance of filament-wound vessels from an organic fiber in several epoxy matrices

    NASA Technical Reports Server (NTRS)

    Chiao, T. T.; Jessop, E. S.; Hamstad, M. A.

    1975-01-01

    A study was carried out to select a state-of-the-art epoxy for wet filament winding. Ten epoxy systems were used to filament wind pressure vessels with a high-modulus, high-strength organic fiber. Data are reported on vessel performance, fiber strand strengths, and shear strengths for the different systems. Using our criteria (processibility, neat resin properties, and vessel performance), we find that an epoxy system based on the rubber-modified bis-phenol-F resin, diluted with vinyl cyclohexane dioxide and cured with mixed aromatic amines, can easily replace bis-phenol-A epoxies diluted with bis-(2, 3-epoxycyclopentyl) ether (such as ERL 2256 epoxy of Union Carbide) with comparable overall performance.

  7. Kinetics of filamentous phage assembly

    NASA Astrophysics Data System (ADS)

    Ploss, Martin; Kuhn, Andreas

    2010-12-01

    Filamentous phages release their progeny particles by a secretory process without lysing the bacterial cell. By this process about 6 viral particles per min are secreted from each cell. We show here that when the major coat protein (gp8) is provided from a plasmid we observe a phage progeny production rate depending on the induction of gp8 by IPTG. We also show that a transfection of Escherichia coli lacking F-pili is observed using a mutant of M13 that carries an ampicillin resistance gene, and phage particles are secreted in the absence of an F-plasmid. Extruding phage was visualized by atomic force microscopy (AFM) and by transmission electron microscopy (TEM) using gold-labeled antibodies to the major coat protein.

  8. Conductive Anodic Filament (CAF) Formation

    NASA Astrophysics Data System (ADS)

    Caputo, Antonio

    Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) which occurs under high humidity and high voltage gradient conditions. The filament, a copper salt, grows from anode to cathode along the epoxy-glass interface. Ready and Turbini (2000) identified this copper salt as the Cu 2(OH)3Cl, atacamite compound. This work has investigated the influence of polyethylene glycol (PEG) and polyethylene propylene glycol (PEPG) fluxing agents on the chemical nature of CAF. For coupons processed with PEPG flux, with and without chloride, a copper-chloride containing compound was formed in the polymer matrix. This compound was characterized using x-ray photoelectron spectroscopy (XPS) as CuCl and an electrochemical mechanism for the formation of the chloride-containing CAF has been proposed. For PEG flux, with and without chloride, it has been shown that CAF only formed, but no copper containing compound formed in the matrix. It appears for PEG fluxed coupons, a PEG-Cu-Cl complex forms, binds the available Cu and acts as a barrier to the formation of CuCl in the polymer matrix. Meeker and Lu Valle (1995) have previously proposed that CAF failure is best represented by two competing reactions -- the formation of a copper chloride corrosion compound (now identified as Cu2(OH)3Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single non-reversible reaction. For coupons processed with a high bromide-containing flux, bromide containing CAF was created and characterized using transmission electron microscopy (TEM) to be Cu2(OH)3Br. In addition, a copper-containing compound was formed in the polymer matrix and characterized using XPS as CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data.

  9. Filamentous Biopolymers on Surfaces: Atomic Force Microscopy Images Compared with Brownian Dynamics Simulation of Filament Deposition

    PubMed Central

    Mücke, Norbert; Klenin, Konstantin; Kirmse, Robert; Bussiek, Malte; Herrmann, Harald; Hafner, Mathias; Langowski, Jörg

    2009-01-01

    Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions. PMID:19888472

  10. Filamentation of Campylobacter in broth cultures

    PubMed Central

    Ghaffar, Nacheervan M.; Connerton, Phillippa L.; Connerton, Ian F.

    2015-01-01

    The transition from rod to filamentous cell morphology has been identified as a response to stressful conditions in many bacterial species and has been ascribed to confer certain survival advantages. Filamentation of Campylobacter jejuni was demonstrated to occur spontaneously on entry in to stationary phase distinguishing it from many other bacteria where a reduction in size is more common. The aim of this study was to investigate the cues that give rise to filamentation of C. jejuni and C. coli and gain insights into the process. Using minimal medium, augmentation of filamentation occurred and it was observed that this morphological change was wide spread amongst C. jejuni strains tested but was not universal in C. coli strains. Filamentation did not appear to be due to release of diffusible molecules, toxic metabolites, or be in response to oxidative stress in the medium. Separated filaments exhibited greater intracellular ATP contents (2.66 to 17.4 fg) than spiral forms (0.99 to 1.7 fg) and showed enhanced survival in water at 4 and 37°C compared to spiral cells. These observations support the conclusion that the filaments are adapted to survive extra-intestinal environments. Differences in cell morphology and physiology need to be considered in the context of the design of experimental studies and the methods adopted for the isolation of campylobacters from food, clinical, and environmental sources. PMID:26175723

  11. On the Fatigue Analysis of Wind Turbines

    SciTech Connect

    Sutherland, Herbert J.

    1999-06-01

    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.

  12. THERMAL AND CHEMICAL EVOLUTION OF COLLAPSING FILAMENTS

    SciTech Connect

    Gray, William J. [Lawrence Livermore National Laboratory, P.O. Box 808, L-038, Livermore, CA 94550 (United States); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1494 (United States)

    2013-05-10

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z Almost-Equal-To 0.1 Z{sub Sun} filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form a dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10{sup -3} Z{sub Sun} filaments, the collapse proceeds much more slowly. This is mostly due to the lower initial temperatures, which lead to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbursting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occurs. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  13. Cross-shelf variability in the Iberian Peninsula Upwelling System: Impact of a mesoscale filament

    NASA Astrophysics Data System (ADS)

    Rossi, Vincent; Garçon, Véronique; Tassel, Joëlle; Romagnan, Jean-Baptiste; Stemmann, Lars; Jourdin, Frédéric; Morin, Pascal; Morel, Yves

    2013-05-01

    Based on a multidisciplinary survey in the Iberian upwelling during late summer 2007, this paper analysed comparatively the cross-shore variability and offshore transport across the upwelling front and within a mesoscale filament. Along the East-West (EW) sections, transient upwelling pulses bring regularly cold, fresh and nutrient-enriched waters to the surface, triggering intense biological responses. Offshore advection by wind-forced Ekman drift of the successive fronts, interrupted by relaxation periods, drive the variability of the planktonic communities. While the near-shore areas are dominated by relatively small phytoplankton controlled by mesozooplankton grazing, large cells of diatoms appear after a short decay. Although microphytoplankton dominates largely the shelf communities, the species composition varies during the offshore drift with the apparition of dinoflagellates and the gradual development of large zooplankton individuals. The oligotrophic ecosystem characterised by small organisms and low biomass (˜80km offshore) contrasts strongly with the transitional area and the coastal upwelling. The low density waters within the filament and the existence of a pair of opposite rotating eddies at its base and tip promote its generation and rapid seaward extension. The intensified offshore advection of coastal enriched waters considerably increases the area favouring a productive ecosystem (until ˜160km off the coast). Cross-shelf variability of bio-physical variables is observed in the filament as along EW sections, although a subsequent homogenisation within the mesoscale structure erases the sharp fronts. Off the shelf within the filament, the chlorophyll a is distinctly organised as a shallow subsurface maximum dominated by nano-phytoplankton. The relative physical isolation of a dynamical food-web in the filament is also promoting nutrient remineralisation under the structure. Finally, we estimate that mesoscale filaments, although being less extended meridionally than the upwelling front itself (˜40% of the length of the front) are responsible for a greater offshore transport of chlorophyll (˜60% of total cross-shelf exchanges) over the Iberian system. Despite the favourable wind pulses advecting westward the successive upwelling fronts, self-propelled filaments provide permanent offshore transport, even under wind relaxation period, thus playing a major role in cross-shelf exchanges.

  14. Can We Determine the Filament Chirality by the Filament Footpoint Location or the Barb-bearing?

    E-print Network

    Hao, Q; Fang, C; Chen, P F; Cao, W

    2015-01-01

    We attempt to propose a method for automatically detecting the solar filament chirality and barb bearing. We first introduce the unweighted undirected graph concept and adopt the Dijkstra shortest-path algorithm to recognize the filament spine. Then, we use the polarity inversion line (PIL) shift method for measuring the polarities on both sides of the filament, and employ the connected components labeling method to identify the barbs and calculate the angle between each barb and the spine to determine the bearing of the barbs, i.e., left or right. We test the automatic detection method with H-alpha filtergrams from the Big Bear Solar Observatory (BBSO) H-alpha archive and magnetograms observed with the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Four filaments are automatically detected and illustrated to show the results. The barbs in different parts of a filament may have opposite bearings. The filaments in the southern hemisphere (northern hemisphere) mainly have ...

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

    E-print Network

    Cambridge, University of

    mover speed is variable, such as in wind turbines. For variable speed operation one of the machine of avoiding the problems associated with brush gear, making the BDFM particularly attractive for offshore wind or generator. The optimization of the machine and model-based control strategies both rely on machine models

  16. The wind program in a typhoon environment

    NASA Astrophysics Data System (ADS)

    Tsao, Y. S.

    The present wind program in the Republic of China (including Taiwan and the off-shore islands under ROC control) is discussed. The collection of wind data in hopeful windmill sites, especially those on offshore islands and coastal areas is discussed. The installation of experimental small wind machines in the above-mentioned sites is described. For example, some small machines will be set up this year in Quemoy for pumping of irrigation water while others will be used for salt-making in the Southern Coast of Taiwan. An evaluation of available Wind energy in Taiwan is given. The assessment of the effect of typhoon on the safety, cost and operation of wind machines is discussed

  17. Experimental study of filamentation in laser–plasma interactions

    Microsoft Academic Search

    P. E. Young

    1991-01-01

    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 that 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.

  18. Experimental study of filamentation in laser-plasma interactions

    Microsoft Academic Search

    P. E. Young

    1991-01-01

    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.

  19. Development of wind turbine towers using fiber reinforced polymers

    NASA Astrophysics Data System (ADS)

    Ungkurapinan, Nibong

    With an ongoing trend in the wind turbine market, the size of wind turbines has been increasing continuously. Larger wind turbines imply an increase in size, weight, and loads acting on the wind turbine tower. This requires towers to be stronger and stiffer, and consequently leads to bigger tower diameters. Because of their size and weight, transportation and erection require heavy equipment that makes the use of such towers prohibitive in remote communities. To tackle this problem, a research program was initiated at the University of Manitoba to develop the technology required for the fabrication of wind turbine towers constructed of fiber reinforced polymers (FRP) for use in remote communities in Canada. The research program was carried out in stages. During the first stage, a feasibility study and an analytical investigation on various shapes of FRP towers were conducted. The concept of a multi-cellular composite tower was examined in great detail and the finite element results showed that such a tower could result in almost 45 percent reduction in weight. In the second stage of this research program, a robotic filament winding machine was designed and constructed in the Composites Laboratory of the University of Manitoba. It was used to fabricate the multi-cell tower specimens for testing. The third stage of the research program involved the experimental investigation, which was carried out in three phases. In the first phase, two single cell specimens were tested to failure under lateral loading. The specimens were 8 ft (2.44 m) long. The second phase involved the testing of two single cells loaded in compression. The third phase of the experimental investigation involved the testing of two eight-cell jointed tower specimens. The specimens were octagonal and tapered, with a diameter of 21.4 in (543 mm) at the base and 17.4 in (441 mm) at the top. They were 16 ft (4.88 m) in height and tested as cantilever under static loading. Local buckling was the dominant failure mode of the specimens tested. One of these towers was subsequently repaired and retested to determine whether repairing would restore the original strength of the tower. The last stage of the research program, various finite element models were developed to analyze the structural behavior of tested specimens. The results from finite element models were validated through comparison with experimental results. The finite element models gave a very good prediction of the structural performance of the FRP towers tested.

  20. Workout Machine

    NASA Technical Reports Server (NTRS)

    1995-01-01

    The Orbotron is a tri-axle exercise machine patterned after a NASA training simulator for astronaut orientation in the microgravity of space. It has three orbiting rings corresponding to roll, pitch and yaw. The user is in the middle of the inner ring with the stomach remaining in the center of all axes, eliminating dizziness. Human power starts the rings spinning, unlike the NASA air-powered system. Marketed by Fantasy Factory (formerly Orbotron, Inc.), the machine can improve aerobic capacity, strength and endurance in five to seven minute workouts.

  1. Filament induced electric events in thunderstorms

    Microsoft Academic Search

    Jean-Pierre Wolf

    2008-01-01

    Following positive laboratory-scale experiments, we investigated the ability to trigger real-scale lightning using ionized filaments generated by ultrashort laser pulses in the atmosphere. Under thunderstorm conditions, we observed electric events synchronized with the laser pulses.

  2. Stretching of buckled filaments by thermal fluctuations

    NASA Astrophysics Data System (ADS)

    Baczynski, Krzysztof; Lipowsky, Reinhard; Kierfeld, Jan

    2007-12-01

    We study the buckling instability of filaments or elastic rods in two spatial dimensions in the presence of thermal fluctuations. We present an analytical solution based on a renormalizationlike procedure where we integrate out short wavelength fluctuations in order to obtain an effective theory governing the buckling instability. We calculate the resulting shift of the critical force by fluctuation effects and the average projected filament length parallel to the force direction as a function of the applied force and of the contour length of the filament. We find that, in the buckled state, thermal fluctuations lead to an increase in the mean projected length of the filament in the force direction. As a function of the contour length, the mean projected length exhibits a cusp at the buckling instability, which becomes rounded by thermal fluctuations. Our analytic results are confirmed by Monte Carlo simulations.

  3. A symplectic integration method for elastic filaments.

    PubMed

    Ladd, Anthony J C; Misra, Gaurav

    2009-03-28

    A new method is proposed for integrating the equations of motion of an elastic filament. In the standard finite-difference and finite-element formulations the continuum equations of motion are discretized in space and time, but it is then difficult to ensure that the Hamiltonian structure of the exact equations is preserved. Here we discretize the Hamiltonian itself, expressed as a line integral over the contour of the filament. This discrete representation of the continuum filament can then be integrated by one of the explicit symplectic integrators frequently used in molecular dynamics. The model systematically approximates the continuum partial differential equations, but has the same level of computational complexity as molecular dynamics and is constraint-free. Numerical tests show that the algorithm is much more stable than a finite-difference formulation and can be used for high aspect ratio filaments, such as actin. PMID:19334891

  4. Snake Filament Eruption - Duration: 5 seconds.

    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...

  5. A symplectic integration method for elastic filaments

    E-print Network

    Ladd, Anthony JC

    2008-01-01

    A new method is proposed for integrating the equations of motion of an elastic filament. In the standard finite-difference and finite-element formulations the continuum equations of motion are discretized in space and time, but it is then difficult to ensure that the Hamiltonian structure of the exact equations is preserved. Here we discretize the Hamiltonian itself, expressed as a line integral over the contour of the filament. This discrete representation of the continuum filament can then be integrated by one of the explicit symplectic integrators frequently used in molecular dynamics. The model systematically approximates the continuum partial differential equations, but has the same level of computational complexity as molecular dynamics and is constraint free. Numerical tests show that the algorithm is much more stable than a finite-difference formulation and can be used for high aspect ratio filaments, such as actin.

  6. Wind-turbine aerodynamics

    Microsoft Academic Search

    R. E. Wilson

    1980-01-01

    The aerodynamics of wind turbines is reviewed starting with effects of lift and drag on translating devices and proceeding through the performance aerodynamics of the horizontal-axis and vertical-axis machines currently in service. Horizontal-axis rotor aerodynamics is outlined and the performance limits are presented along with key assumptions and problem areas. The Darrieus rotor multiple streamtube analysis is developed and compared

  7. The VGOT Darrieus wind turbine

    Microsoft Academic Search

    Fernando L. Ponta; Alejandro D. Otero; Lucas Lago

    2004-01-01

    We present the actual state of development of a non-conventional new vertical-axis wind turbine. The concepts introduced here involve the constructive aspects of variable-geometry oval-trajectory (VGOT) Darrieus wind turbines. The key feature of a VGOT machine is that each blade slides over rails mounted on a wagon instead of rotating around a central vertical axis. Each wagon contains its own

  8. Kinks, rings, and rackets in filamentous structures

    PubMed Central

    Cohen, Adam E.; Mahadevan, L.

    2003-01-01

    Carbon nanotubes and biological filaments each spontaneously assemble into kinked helices, rings, and “tennis racket” shapes due to competition between elastic and interfacial effects. We show that the slender geometry is a more important determinant of the morphology than any molecular details. Our mesoscopic continuum theory is capable of quantifying observations of these structures and is suggestive of their occurrence in other filamentous assemblies as well. PMID:14530401

  9. Driven Diffusive Systems of Active Filament Bundles

    Microsoft Academic Search

    P. K. Mohanty; K. Kruse

    2007-01-01

    The cytoskeleton is an important subsystem of cells that is involved for example in cell division and locomotion. It consists\\u000a of filaments that are cross-linked by molecular motors that can induce relative sliding between filaments and generate stresses\\u000a in the network. In order to study the effects of fluctuations on the dynamics of such a system we introduce here a

  10. Filament-wound, fiberglass cryogenic tank supports

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

    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.

  11. Design and Testing of a Permanent Magnet Axial Flux Wind Power Generator

    Microsoft Academic Search

    Garrison F. Price; Todd D. Batzel; Mihai Comanescu; Bruce A. Muller

    The axial flux (disc shape) permanent magnet machine is an attractive alternative to radial flux (cylindrical shape) machines in wind turbine applications. The axial flux configuration is amenable to the low-speed, high-torque operation of a direct drive wind energy system. Direct drive wind energy conversion tends to decrease the system size, weight, and noise, while increasing overall efficiency and reliability.

  12. Experimental study of filamentation in laser-plasma interactions

    SciTech Connect

    Young, P.E.

    1991-01-07

    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.

  13. Tensile Properties of Single Desmin Intermediate Filaments

    PubMed Central

    Kreplak, Laurent; Herrmann, Harald; Aebi, Ueli

    2008-01-01

    Within muscle fibers, desmin intermediate filaments (IFs) are major constituents of the extrasarcomeric cytoskeleton. However, their contribution to the mechanical properties of myocytes has remained elusive. We present an experimental approach to measure the extensibility and the tensile strength of in vitro reconstituted desmin IFs adsorbed to a solid support. The tip of an atomic force microscope (AFM) was used to push on single filaments perpendicular to the filament axis. The torque of the AFM cantilever was monitored during the pushing events to yield an estimate of the lateral force necessary to bend and stretch the filaments. Desmin IFs were stretched up to 3.4-fold with a maximum force of ?3.5 nN. Fully stretched filaments exhibited a much smaller diameter than did native IFs, i.e., ?3.5 nm compared to 12.6 nm, both by AFM and electron microscopy. Moreover, we combined the morphological and lateral force data to compute an average stress-strain curve for a single desmin filament. The main features were a pronounced strain-hardening regime above 50% extension and a tensile strength of at least 240 MPa. Because of these nonlinear tensile properties, desmin IFs may dissipate mechanical energy and serve as a physical link between successive sarcomeres during large deformation. PMID:18178641

  14. A Straight and Narrow Ionized Filament

    E-print Network

    Peter R. McCullough; Robert A. Benjamin

    2001-05-21

    We report the discovery of a extremely narrow, extremely linear, ionized filament. The filament is 2.5 degrees long and has an H$\\alpha$ surface brightness of 0.5 rayleighs. The filament is approximately ``Y'' shaped. The widest separation of the two diagonal segments is 5 arcminutes. We discuss four possible origins for this feature: (1) an extremely low density, nearby jet, (2) an unusually linear filament associated with some large-scale nearby nebula, perhaps even the Local Bubble, (3) an ionized trail left by mechanical input from a star or compact object moving through the ISM, or (4) an ionized trail left by photoionization (``Fossil \\stromgren Trail'') from a star or compact object. We favor this last hypothesis, and derive some of the basic properties for an ionized trail. Regardless of whether this latter hypothesis applies to this specific filament, the basic properties of such a trail, its length, width, and brightness, are interesting, predictable, and should be observable behind some white dwarfs. We suggest future tests for ascertaining the origin of this filament, and discuss how this structure might be useful to constrain the thermal and velocity structure of the nearby interstellar medium.

  15. Function Machine

    NSDL National Science Digital Library

    2011-01-01

    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.

  16. Decoding Machine

    NSDL National Science Digital Library

    2012-10-22

    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.

  17. Proper Motions and Brightness Variations of Nonthermal X-ray Filaments in the Cassiopeia A Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Patnaude, Daniel J.; Fesen, Robert A.

    2009-05-01

    We present Chandra ACIS X-ray observations of the Galactic supernova remnant Cassiopeia A taken in 2007 December. Combining these data with previous archival Chandra observations taken in 2000, 2002, and 2004, we estimate the remnant's forward shock velocity at various points around the outermost shell to range between 4200 and 5200 ± 500 km s-1. Using these results together with previous analyses of Cas A's X-ray emission, we present a model for the evolution of Cas A and find that it's expansion is well fit by a ?ej vprop r -(7-9) ejecta profile running into a circumstellar wind. We further find that while the position of the reverse shock in this model is consistent with that measured in the X-rays, in order to match the forward shock velocity and radius we had to assume that ~ 30% of the explosion energy has gone into accelerating cosmic rays at the forward shock. The new X-ray images also show that brightness variations can occur for some forward shock filaments like that seen for several nonthermal filaments seen projected in the interior of the remnant. Spectral fits to exterior forward shock filaments and interior nonthermal filaments show that they exhibit similar spectra. This together with similar flux variations suggests that interior nonthermal filaments might be simply forward shock filaments seen in projection and not located at the reverse shock as has been recently proposed.

  18. Solar filament impact on 21 January 2005: Geospace consequences

    NASA Astrophysics Data System (ADS)

    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

    On 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.

  19. Monitoring the integrity of filament-wound structures using built-in sensor networks

    NASA Astrophysics Data System (ADS)

    Lin, Mark; Kumar, Amrita; Qing, Xinlin; Beard, Shawn J.; Russell, Samuel S.; Walker, James L.; Delay, Thomas K.

    2003-08-01

    Monitoring the integrity of filament wound composite structures such as solid rocket motors and liquid fuel bottles is important in order to prevent catastrophic failures and to prolong the service life of these structures. To ensure the safety and reliability of rocket components, they require frequent inspection for structural damages that might have occurred during manufacturing, transportation, and storage. The timely and accurate detection, characterization and monitoring of structural cracking, delamination, debonding and other types of damage is a major concern in the operational environment. Utilization of a sensor network system integrated with the structure itself can greatly reduce this inspection burden through fast in-situ data collection and processing. Acellent Technologies, Inc. is currently developing integrated structural monitoring tools for continuous monitoring of composite and metal structures on aircraft and spacecraft. Acellent's integrated structural monitoring system consists of a flexible sensor/actuator network layer called the SMART Layer, supporting diagnostic hardware, and data processing/analysis software. Recently, Acellent has been working with NASA Marshall Space Flight Center to develop ways of embedding the SMART Layer inside filament wound composite bottles. SMART Layers were designed and manufactured for the filament wound bottles and embedded in them during the filament winding process. Acellent has been working on developing a complete structural health monitoring system for the filament wound bottles including data processing tools to interpret the changes in sensor signal caused by changes in the structural condition or material property. A prototype of a filament wound composite bottle with an embedded sensor network has been fabricated and preliminary data analysis tools have been developed.

  20. Performance analysis of synchronous machines under dynamic eccentricity 

    E-print Network

    Al-Nuaim, Nabil Abdulaziz

    1996-01-01

    The performance of salient pole synchronous machines under eccentric rotors is studied. Relationships between stator and rotor current induced harmonics and dynamic eccentricity are investigated. The winding function theory has been modified...

  1. A wake detector for wind farm control

    NASA Astrophysics Data System (ADS)

    Bottasso, C. L.; Cacciola, S.; Schreiber, J.

    2015-06-01

    The paper describes an observer capable of detecting the impingement on a wind turbine rotor of the wake of an upstream machine. The observer estimates the local wind speed and turbulence intensity on the left and right parts of the rotor disk. The estimation is performed based on blade loads measured by strain gages or optical fibers, sensors which are becoming standard equipment on many modern machines. A lower wind speed and higher turbulence intensity on one part of the rotor, possibly in conjunction with other information, can then be used to infer the presence of a wake impinging on the disk. The wake state information is useful for wind plant control strategies, as for example wake deflection by active yawing. In addition, the local wind speed estimates may be used for a rough evaluation of the vertical wind shear.

  2. Machine Learning

    NASA Astrophysics Data System (ADS)

    Hoffmann, Achim; Mahidadia, Ashesh

    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.

  3. Filament Activation in Response to Magnetic Flux Emergence and Cancellation in Filament Channels

    E-print Network

    Li, Ting; Ji, Haisheng

    2015-01-01

    We make a comparative analysis for two filaments that showed quite different activation in response to the flux emergence within the filament channels. The observations from the Solar Dynamics Observatory (SDO) and Global Oscillation Network Group (GONG) are carried out to analyze the two filaments on 2013 August 17-20 and September 29. The first event showed that the main body of the filament was separated into two parts when an active region (AR) emerged with a maximum magnetic flux of about 6.4*10^21 Mx underlying the filament. The close neighborhood and common direction of the bright threads in the filament and the open AR fan loops suggest similar magnetic connectivity of these two flux systems. The equilibrium of the filament was not destroyed within 3 days after the start of the emergence of the AR. To our knowledge, similar observations have never been reported before. In the second event, the emerging flux occurred nearby a barb of the filament with a maximum magnetic flux of 4.2*10^20 Mx, about one ...

  4. Filament eruption in association with rotational motion near the filament footpoints

    E-print Network

    Dhara, Sajal Kumar; Banyal, Ravinder Kumar

    2013-01-01

    The active region magnetic field surrounding the filament plays an important role in filament formation, their evolution and disruption. We investigated a filament eruption that occurred in southern hemisphere of the Sun on July 08, 2011 using AIA and HMI data. The filament was located in a region close to the active region NOAA 11247 with its West-most footpoint anchored in the negative polarity plage region and the East-most in the positive polarity plage region. During observations, the magnetic flux was emerging in the active region and also in the plage regions. The flux emergence was stopped in West-most footpoint of the plage region about an hour before the filament eruption. A converging motion was also observed for many hours in the Western footpoint of the filament. The filament had left-handed twist and the net injected magnetic helicity was positive in both footpoints. Both sign of magnetic helicity were observed in the Western footpoint of the filament where the eruption has initiated. Further, a...

  5. Dynamic behavior of variable speed wind turbines under stochastic wind

    Microsoft Academic Search

    S. A. Papathanassiou; M. P. Papadopoulos

    1999-01-01

    It is recognized that the most important advantage of the variable speed wind turbines (VS WTs) over the conventional constant speed (CS) machines are the improved dynamic characteristics, resulting in the reduction of the drive train mechanical stresses and output power fluctuations. In this paper alternative configurations of the electrical part of a VS WT are considered, using a squirrel

  6. Wind height distribution influence on offshore wind farm feasibility study

    NASA Astrophysics Data System (ADS)

    Benassai, Guido; Della Morte, Renata; Matarazzo, Antonio; Cozzolino, Luca

    2015-04-01

    The economic feasibility of offshore wind power utilization depends on the favourable wind conditions offshore as compared to sites on land. The higher wind speeds have to compensate the additional cost of offshore developments. However, not only the mean wind speed is different, but the whole flow regime, as can be seen in the vertical wind speed profile. The commonly used models to describe this profile have been developed mainly for land sites, so they have to be verified on the basis of field data. Monin-Obukhov theory is often used for the description of the wind speed profile at a different height with respect to a measurement height. Starting from the former, , the profile is predicted using two parameters, Obukhov length and sea surface roughness. For situations with near-neutral and stable atmospheric stratification and long (>30km) fetch, the wind speed increase with height is larger than what is predicted from Monin-Obukhov theory. It is also found that this deviation occurs at wind speeds important for wind power utilization, mainly at 5-9 ms-1. In the present study the influence of these aspects on the potential site productivity of an offshore wind farm were investigated, namely the deviation from the theory of Monin-Obukhov due to atmospheric stability and the influence of the fetch length on the Charnock model. Both these physical effects were discussed and examined in view of a feasibility study of a site for offshore wind farm in Southern Italy. Available data consisted of time histories of wind speeds and directions collected by National Tidegauge Network (Rete Mareografica Nazionale) at the height of 10m a.s.l. in ports. The theory of Monin-Obukhov was used to extrapolate the data to the height of the wind blades, while the Charnock model was used to extend the wind speed on the sea surface from the friction velocity on the ground. The models described were used to perform calculations for a feasibility study of an offshore wind farm in Southern Italy. The potential site productivity was established on the basis of the wind speed distribution function for different heights (site specific) and the power law of the wind turbine considered, as a function of the wind speed at the nacelle height (machine specific). The results of the optimization study for different sites and different wind turbines were compared with the power estimates of Italian Wind Atlas, which provided useful insights for further study.

  7. Simple Machines

    NSDL National Science Digital Library

    Wakild, Terri

    The goals for this introduction activity to Simple Machines are.: - Generate scientific questions about the world based on observation - Design and conduct scientific investigations - Use tools and equipment appropriate to scientific investigations - Use sources of information in support of scientific investigation - Write and follow procedures in the form of step-by-step instructions, formulas, flow diagram, and sketches - Show how common themes of science, mathematics, and technology apply in real-world contexts - Recognize the contributions made in science by cultures and individuals of diverse backgrounds - Design strategies for moving objects by application of forces, including the use of simple machines MERC Online Reviewer Comments: Good computer activities for under-represented students who want to pursue manufacturing education. Distance Learning is a plus.

  8. Unwinding motion of a twisted active-region filament

    E-print Network

    Yan, X L; Liu, J H; Kong, D F; Xu, C L

    2014-01-01

    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 June 22, 2010. 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 is consisted of twisted magnetic field lines. The total twist of the filament is at least 5$\\pi$ obtained by using 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 magn...

  9. Simple Machines

    NSDL National Science Digital Library

    Miss Stewart

    2010-03-24

    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 ...

  10. Mining machine

    SciTech Connect

    Mendola, C.F.

    1981-11-03

    A mining machine is disclosed in which a cutting drum undercuts a vein of coal and side relief cutters make vertical kerfs in the vein upwardly from the undercut. A chisel plate is forced into the coal vein and breaks loose the material above the undercut and between the side relief cuts. The coal falls into conveyors and is loaded into mine shuttle cars for removal from the mine. The side relief cutters and chisel assembly are progressively raised to extract higher levels of coal from the vein until the desired roof height has been reached. The tramming track assembly, which propels the machine, may be rotated 90/sup 0/ to permit extraction from the vein immediately adjacent the initial extraction. All power supplied near the working face of the vein is hydraulic to minimize the risk of fire or explosion, and a water spray system minimizes dust circulation. Hydraulic roof and floor jacks are provided to increase the stability of the mining machine when exceptionally hard material is encountered in the coal vein.

  11. Wind Power: A Turning Point. Worldwatch Paper 45.

    ERIC Educational Resources Information Center

    Flavin, Christopher

    Recent studies have shown wind power to be an eminently practical and potentially substantial source of electricity and direct mechanical power. Wind machines range from simple water-pumping devices made of wood and cloth to large electricity producing turbines with fiberglass blades nearly 300 feet long. Wind is in effect a form of solar…

  12. Modeling and control of a wind turbine driven doubly fed induction generator

    Microsoft Academic Search

    Arantxa Tapia; Gerardo Tapia; J. Xabier Ostolaza; José Ramón Sáenz

    2003-01-01

    This paper presents the simulation results of a grid-connected wind driven doubly fed induction machine (DFIM) together with some real machine performance results. The modeling of the machine considers operating conditions below and above synchronous speed, which are actually achieved by means of a double-sided PWM converter joining the machine rotor to the grid. In order to decouple the active

  13. The HWP-300 wind turbine

    NASA Astrophysics Data System (ADS)

    Jamieson, P.; McLeish, D.

    1983-12-01

    A 300 kW, 22 m diameter wind turbine has been designed and erected (July 1983) on the site of the North of Scotland Hydro-Electric Board at Burgar Hill in Orkney. The machine and its design concepts are described.

  14. Erosion: Wind

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion refers to the detachment, transport and deposition of sediment by wind. It is a dynamic, physical process where loose, dry, bare soils are transported by strong winds. Wind erosion is a soil degrading process that affects over 500 million ha of land worldwide and creates between 500 an...

  15. Paralleling the stator coils in permanent magnet machines

    Microsoft Academic Search

    Mohammad S. Islam; Sayeed Mir; Tomy Sebastian

    2005-01-01

    As low voltage machines require smaller number of turns per phase compared to higher voltage machines, it is normal to connect the various stator phase coils in parallel to form the phase winding. The placement of various coil sides in the slot and the difference in the field produced by different poles of the rotor magnet can influence the induced

  16. MICROPROCESSOR BASED NONLINEAR EXCITATION CONTROLLER FOR SYNCHRONOUS MACHINES

    Microsoft Academic Search

    TOMONOBU SENJYU; KATSUMI UEZATO

    1996-01-01

    The synchronous machines in power systems have the excitation systems of field winding to improve the transient stability of power systems. The synchronous machines are nonlinear systems, however, the excitation systems have been designed based on linearized systems, because the stability analysis of nonlinear systems is difficult and the generalized control method of nonlinear systems has not been developed yet.This

  17. Exact and Volterra analysis of synchronous machine stability

    Microsoft Academic Search

    F. FALLSIDE; J. WADDINGTON

    1970-01-01

    The stability of unsaturated, round-rotor synchronous machines is investigated from a mathematical model which includes winding resistance, leakage reactance and iron loss. Under certain conditions an exact boundary can be obtained and very close agreement is obtained between it and experimental results. The effect on stability of varying the machine loading is demonstrated.When stator resistance and iron loss are neglected

  18. SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS

    SciTech Connect

    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

    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.

  19. Filament velocity scaling laws for warm ions

    NASA Astrophysics Data System (ADS)

    Manz, P.; Carralero, D.; Birkenmeier, G.; Müller, H. W.; Müller, S. H.; Fuchert, G.; Scott, B. D.; Stroth, U.

    2013-10-01

    The dynamics of filaments or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvén fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of filaments amongst others by adding up to the interchange drive and the polarisation current. It is shown how both effects modify the scaling laws for filament velocity in dependence of its size. Simplifications for experimentally relevant limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.

  20. Filament velocity scaling laws for warm ions

    SciTech Connect

    Manz, P. [Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany) [Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany); Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Carralero, D.; Birkenmeier, G.; Müller, H. W.; Scott, B. D. [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany)] [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Müller, S. H. [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego 92093 (United States)] [Center for Momentum Transport and Flow Organization, University of California at San Diego, San Diego 92093 (United States); Fuchert, G. [Insitut für Grenzflächenverfahrenstechnik und Plasmatechnologie, Universität Stuttgart, 70569 Stuttgart (Germany)] [Insitut für Grenzflächenverfahrenstechnik und Plasmatechnologie, Universität Stuttgart, 70569 Stuttgart (Germany); Stroth, U. [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany) [Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching (Germany); Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany)

    2013-10-15

    The dynamics of filaments or blobs in the scrape-off layer of magnetic fusion devices are studied by magnitude estimates of a comprehensive drift-interchange-Alfvén fluid model. The standard blob models are reproduced in the cold ion case. Even though usually neglected, in the scrape-off layer, the ion temperature can exceed the electron temperature by an order of magnitude. The ion pressure affects the dynamics of filaments amongst others by adding up to the interchange drive and the polarisation current. It is shown how both effects modify the scaling laws for filament velocity in dependence of its size. Simplifications for experimentally relevant limit regimes are given. These are the sheath dissipation, collisional, and electromagnetic regime.

  1. Recurrent filament eruptions and associated CMEs

    NASA Astrophysics Data System (ADS)

    Schmieder, Brigitte; Cremades, Hebe; Mandrini, Cristina; Démoulin, Pascal; Guo, Yang

    2014-01-01

    We investigate the violent events in the cluster of two active regions (ARs), NOAA numbers 11121 and 11123, observed on 11 November 2010 by the Solar Dynamics Observatory (SDO). Within one day the magnetic field intensity increased by 70% with the emergence of new groups of bipoles in AR 11123, where three filaments are seen along the complex inversion line. The destabilization of the filaments led to flares and CMEs. The CMEs around 08:24 UT and 17:00 UT are directly related to the partial eruption of one filament in the new AR, as shown by a topology computation and analysis. The other CMEs on this day are due to either other ARs or to the destabilization of the global magnetic configuration of the two ARs. This conclusion can be only reached by using the three eyes of SOHO, STEREO and SDO.

  2. Filament Twist in F-Actin Bundles

    NASA Astrophysics Data System (ADS)

    Angelini, Tommy; Sanders, Lori; Wong, Gerard

    2003-03-01

    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.

  3. Learning about Simple Machines

    NSDL National Science Digital Library

    Mrs. Keller

    2010-01-17

    This activity is designed to learn about simple machines and to have fun doing so! First, use this website to learn backround information on the basics of simple machines. Try the quiz! Simple Machines Learning Site Next, play a game that tests your ability to identify simple machines.... Edheads: Simple Machines Finally, view this video to see how students your age used applied simple machines to do a cool task... Building Simple Machines: A Glass of Milk, Please ...

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Soto, Leopoldo; Pavez, Cristian; Castillo, Fermin; Veloso, Felipe; Moreno, José; Auluck, S. K. H.

    2014-07-01

    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.

  6. Infrared Radiation Filament And Metnod Of Manufacture

    DOEpatents

    Johnson, Edward A. (Bedford, MA)

    1998-11-17

    An improved IR radiation source is provided by the invention. A radiation filament has a textured surface produced by seeded ion bombardment of a metal foil which is cut to a serpentine shape and mounted in a windowed housing. Specific ion bombardment texturing techniques tune the surface to maximize emissions in the desired wavelength range and to limit emissions outside that narrow range, particularly at longer wavelengths. A combination of filament surface texture, thickness, material, shape and power circuit feedback control produce wavelength controlled and efficient radiation at much lower power requirements than devices of the prior art.

  7. 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.

  8. The Origin of the Galactic Center Nonthermal Radio Filaments: Young Stellar Clusters

    E-print Network

    F. Yusef-Zadeh

    2003-08-01

    The unusual class of magnetized nonthermal radio filaments (NTF), threads and streaks with their unique physical characteristics are found only within the inner couple of degrees of the Galactic center. Also, a number of young, mass-losing and rare stellar clusters are recognized to lie in the Galactic center region. The latter characteristic of the Galactic center region is used to explain the origin of the nonthermal radio filaments. We consider a mechanism in which the collective winds of massive WR and OB stars within a dense stellar environment produce shock waves that can accelerate particles to relativistic energies. This mechanism is an extension of a model originally proposed by Rosner and Bodo (1996), who suggested that energetic nonthermal particles are produced in a terminal shock of mass-losing stars. The large-scale distribution of the magnetic field in the context of this model is argued to have neither poloidal geometry nor pervasive throughout the Galactic center region.

  9. Questions Concerning the Disconnection and Eruption of Filaments and CMEs

    NASA Technical Reports Server (NTRS)

    Kucera, Theresa

    2007-01-01

    Reviews examples of eruptions and failed eruptions of filaments and CMEs and review questions concerning the processes and mechanisms involved. Where and how does disconnection occur? What can we learn (if anything!) about CME eruptions by observing related filament eruptions?

  10. Dynamics of filament formation in a Kerr medium

    SciTech Connect

    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

    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.

  11. Dual-rotor, radial-flux, toroidally-wound, permanent-magnet machine

    DOEpatents

    Qu, Ronghai; Lipo, Thomas A.

    2005-08-02

    The present invention provides a novel dual-rotor, radial-flux, toroidally-wound, permanent-magnet machine. The present invention improves electrical machine torque density and efficiency. At least one concentric surface-mounted permanent magnet dual-rotor is located inside and outside of a torus-shaped stator with back-to-back windings, respectively. The machine substantially improves machine efficiency by reducing the end windings and boosts the torque density by at least doubling the air gap and optimizing the machine aspect ratio.

  12. A Five-Phase Brushless DC-Machine Direct Drive System EPE Journal Vol. 14 no

    E-print Network

    Simões, Marcelo Godoy

    where an induction machine with asymmetric windings has three-phase sets advanced by 30 degreesA Five-Phase Brushless DC-Machine Direct Drive System EPE Journal Vol. 14 no 3 August 2004 15. Three-phase drive systems have been widely used for years because of the availability of such machines

  13. Course info Machine Learning

    E-print Network

    Shi, Qinfeng "Javen"

    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

  14. Hybrid-secondary uncluttered induction machine

    DOEpatents

    Hsu, John S. (Oak Ridge, TN)

    2001-01-01

    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.

  15. Mechanical heterogeneity favors fragmentation of strained actin filaments.

    PubMed

    De La Cruz, Enrique M; Martiel, Jean-Louis; Blanchoin, Laurent

    2015-05-01

    We present a general model of actin filament deformation and fragmentation in response to compressive forces. The elastic free energy density along filaments is determined by their shape and mechanical properties, which were modeled in terms of bending, twisting, and twist-bend coupling elasticities. The elastic energy stored in filament deformation (i.e., strain) tilts the fragmentation-annealing reaction free-energy profile to favor fragmentation. The energy gradient introduces a local shear force that accelerates filament intersubunit bond rupture. The severing protein, cofilin, renders filaments more compliant in bending and twisting. As a result, filaments that are partially decorated with cofilin are mechanically heterogeneous (i.e., nonuniform) and display asymmetric shape deformations and energy profiles distinct from mechanically homogenous (i.e., uniform), bare actin, or saturated cofilactin filaments. The local buckling strain depends on the relative size of the compliant segment as well as the bending and twisting rigidities of flanking regions. Filaments with a single bare/cofilin-decorated boundary localize energy and force adjacent to the boundary, within the compliant cofilactin segment. Filaments with small cofilin clusters were predicted to fragment within the compliant cofilactin rather than at boundaries. Neglecting contributions from twist-bend coupling elasticity underestimates the energy density and gradients along filaments, and thus the net effects of filament strain to fragmentation. Spatial confinement causes compliant cofilactin segments and filaments to adopt higher deformation modes and store more elastic energy, thereby promoting fragmentation. The theory and simulations presented here establish a quantitative relationship between actin filament fragmentation thermodynamics and elasticity, and reveal how local discontinuities in filament mechanical properties introduced by regulatory proteins can modulate both the severing efficiency and location along filaments. The emergent behavior of mechanically heterogeneous filaments, particularly under confinement, emphasizes that severing in cells is likely to be influenced by multiple physical and chemical factors. PMID:25954884

  16. Start up and control of a DFIG wind turbine test rig

    Microsoft Academic Search

    J. A. Cortajarena; J. De Marcos; P. Alvarez; F. J. Vicandi; P. Alkorta

    2011-01-01

    Power generated from wind is a fast growing renewable source of the world energy consumption. A test bench for comprehensive research on the doubly fed induction generator (DFIG) used as wind turbine is implemented. The wind energy is emulated with a synchronous machine according to the wind profile specified in the computer. Two inverters in a back to back configuration

  17. Electric events synchronized with laser filaments in thunderclouds.

    PubMed

    Kasparian, Jérôme; Ackermann, Roland; André, Yves-Bernard; Méchain, Grégoire; Méjean, Guillaume; Prade, Bernard; Rohwetter, Philipp; Salmon, Estelle; Stelmaszczyk, Kamil; Yu, Jin; Mysyrowicz, André; Sauerbrey, Roland; Wöste, Ludger; Wolf, Jean-Pierre

    2008-04-14

    We investigated the possibility to trigger real-scale lightning using ionized filaments generated by ultrashort laser pulses in the atmosphere. Under conditions of high electric field during two thunderstorms, we observed a statistically significant number of electric events synchronized with the laser pulses, at the location of the filaments. This observation suggests that corona discharges may have been triggered by filaments. PMID:18542684

  18. Tungsten filament as reinforcement for heat resistant composite materials

    Microsoft Academic Search

    N. M. Fonshtein; G. N. Tikhomirova; V. F. Kotov; V. I. Shvarts

    1971-01-01

    Fine tungsten filament is a promising reinforcement for composite materials. This is due to the good properties of alloys based on tungsten - high recrystallizatio n temperature, high strength and modulus of elasticity in a fairly wide temperature range, and, particularly valuable, deformability of a continuous filament with a diameter from a few microns to several millimeters. Thin filaments are

  19. Potential fields of merging and splitting filaments in air

    Microsoft Academic Search

    Yuan-Yuan Ma; Xin Lu; Ting-Ting Xi; Zuo-Qiang Hao; Qi-Huang Gong; Jie Zhang

    2007-01-01

    Two interacting light filaments with different initial phases propagating in air are investigated numerically by using a ray tracing method. The evolution of the rays of a filament is governed by a potential field. During propagation, the two potential wells of the two filaments can merge into one or repel each other, depending on the initial phase difference between the

  20. Conductivity Measurements of Femtosecond Laser–Plasma Filaments

    Microsoft Academic Search

    Richard P. Fischer; Antonio C. Ting; Daniel F. Gordon; Richard F. Fernsler; Gregory P. DiComo; Phillip Sprangle

    2007-01-01

    Experiments are performed to characterize the electrical properties of plasma filaments that are generated by self- guided femtosecond laser pulses propagating in air. A single plasma filament passes through a high-voltage sphere pulsed at -100 kV to a grounded electrode, which serves as a current monitor. The experiments utilize moderate electric fields to probe the filament conductivity, thereby avoiding the

  1. Exact solution for the extensional flow of a viscoelastic filament

    Microsoft Academic Search

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

    2004-01-01

    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

  2. Experimental investigation into ELM filament formation on MAST

    Microsoft Academic Search

    R. Scannell; A. Kirk; N. Ben Ayed; P. G. Carolan; G. Cunningham; J. McCone; S. L. Prunty; M. J. Walsh

    2007-01-01

    Radial profiles of electron temperature and density through type I ELM filaments have been obtained from a new edge Thomson scattering diagnostic at MAST. The lasers were fired in burst mode, 5 µs apart, to study profile evolution of a single filament as it moves toroidally past the laser beams. The plasma particle and energy loss due to each filament

  3. Mechanism of Actin Filament Bundling by Fascin

    Microsoft Academic Search

    Silvia Jansen; Agnieszka Collins; Changsong Yang; Grzegorz Rebowski; Tatyana Svitkina; Roberto Dominguez

    2011-01-01

    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 β-trefoil domains. Here, we show that fascin contains two major actin-binding

  4. Hawking radiation from ultrashort laser pulse filaments

    E-print Network

    F. Belgiorno; S. L. Cacciatori; M. Clerici; V. Gorini; G. Ortenzi; L. Rizzi; E. Rubino; V. G. Sala; D. Faccio

    2010-09-23

    Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.

  5. FILAMENTATION INDUCED NONLINEAR OPTICS Doctorat en Physique

    E-print Network

    equilibrium between Kerr self-focusing and defocusing by the self-generated plasma produced by multiphoton. D) Québec, Canada © Shuai Yuan, 2014 #12;#12;Résumé La filamentation du laser femtoseconde provient. Ceux-ci sont la rotation de la polarisation laser dans les gaz atomiques/moléculaires, le processus d

  6. SECONDARY METABOLIC GENE CLUSTERS IN FILAMENTOUS FUNGI

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Filamentous fungi produce a number of secondary metabolic compounds that have been shown to be both of great value (i.e. antibiotics and anti-hypercholesterolemics) and great harm (i.e. aflatoxins and trichothecenes). The genes responsible for producing the secondary metabolite are often clustered ...

  7. Radial interchange motions of plasma filaments

    SciTech Connect

    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

    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.

  8. 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 Many of the commercial production processes for organic acids are excellent examples of fungal biotechnology. However, unlike penicillin, the organic acids have had a less vis- ible impact on human well

  9. Filamentation of a Magnetized, Radio Frequency Discharge

    NASA Astrophysics Data System (ADS)

    Konopka, Uwe; Lynch, Brian; Bandyopadhyay, Pintu; Sharma, Devendra; Thomas, Edward

    2014-10-01

    A filamentation instability has been observed in a radio-frequency (rf) discharge that was subject to an externally applied, homogeneous magnetic field. The instability arises in a uniform rf-discharge after the magnetic field strength is sufficiently increased. First, the plasma shows target-like glow structures, followed by spiral structures at higher fields. Finally, the plasma breaks up into individual, string-like, magnetic field aligned filaments that seem to repel each other. A variety of filamentation states can be observed, but their overall shapes follow the aforementioned rule of magnetic field strength dependency. The detailed picture of the discharge glow, however, depends on experiment specific conditions as the geometric shape and type of the discharge electrodes, the discharge pressure and power. In an effort to verify that the observed effect is universal, we compare experimental measurements made using two different high magnetic field, dusty plasma experiment facilities: the experiment that was located at the Max Planck Institute in Garching, Germany and the newly built MDPX (magnetized dusty plasma experiment) at Auburn University, Alabama. In both experimental setups we could observe filamentation. This work is supported from funding from DOE and NSF.

  10. Automated Filament Finding and Selection from Cryo

    E-print Network

    Illinois at Urbana-Champaign, University of

    . In addition, statistical methods are used to split two filaments if they are joined together end to end. Phase correlation is a method based upon the inverse Fourier transform of the phase difference between two images3. The computation of the phase correlation map consists of three steps: (i) a 2D fast Fourier transform (FFT

  11. Organizing Multiple Femtosecond Filaments in Air

    Microsoft Academic Search

    G. Méchain; A. Couairon; M. Franco; B. Prade; A. Mysyrowicz

    2004-01-01

    We show that it is possible to organize regular filamentation patterns in air by imposing either strong field gradients or phase distortions in the input-beam profile of an intense femtosecond laser pulse. A comparison between experiments and 3+1 dimensional numerical simulations confirms this concept and shows for the first time that a control of the transport of high intensities over

  12. Optical Vortex Filaments Grover A. Swartzlander, Jr.

    E-print Network

    Swartzlander Jr., Grover A.

    -clockwise), as described r r r Rj x y j j r rj y'j x'j 2wV Figure 1. Intensity profile of a Gaussian laser beamOptical Vortex Filaments Grover A. Swartzlander, Jr. Physics Department Worcester Polytechnic dynamics of neighboring optical vortices in the same beam. When the core is small compared to the distance

  13. Ion beam propagation in a filamented channel

    Microsoft Academic Search

    P. F. Ottinger; S. A. Goldstein; D. Moster

    1980-01-01

    The production of intense focused ion beams led to the consideration of using z-discharge plasma channels to transport them several meters to inertial fusion targets. Current bunching will occur in the channel during transport. Ion beam propagation in a filamented channel was investigated in order to determine the effects on radial beam containment in channels and on the radial beam

  14. Light sources based on semiconductor current filaments

    DOEpatents

    Zutavern, Fred J. (Albuquerque, NM); Loubriel, Guillermo M. (Albuquerque, NM); Buttram, Malcolm T. (Sandia Park, NM); Mar, Alan (Albuquerque, NM); Helgeson, Wesley D. (Albuquerque, NM); O'Malley, Martin W. (Edgewood, NM); Hjalmarson, Harold P. (Albuquerque, NM); Baca, Albert G. (Albuquerque, NM); Chow, Weng W. (Cedar Crest, NM); Vawter, G. Allen (Albuquerque, NM)

    2003-01-01

    The present invention provides a new type of semiconductor light source that can produce a high peak power output and is not injection, e-beam, or optically pumped. The present invention is capable of producing high quality coherent or incoherent optical emission. The present invention is based on current filaments, unlike conventional semiconductor lasers that are based on p-n junctions. The present invention provides a light source formed by an electron-hole plasma inside a current filament. The electron-hole plasma can be several hundred microns in diameter and several centimeters long. A current filament can be initiated optically or with an e-beam, but can be pumped electrically across a large insulating region. A current filament can be produced in high gain photoconductive semiconductor switches. The light source provided by the present invention has a potentially large volume and therefore a potentially large energy per pulse or peak power available from a single (coherent) semiconductor laser. Like other semiconductor lasers, these light sources will emit radiation at the wavelength near the bandgap energy (for GaAs 875 nm or near infra red). Immediate potential applications of the present invention include high energy, short pulse, compact, low cost lasers and other incoherent light sources.

  15. Applications of Submicron Diameter Carbon Filaments

    Microsoft Academic Search

    D. D. L. Chung

    \\u000a The applications of submicron diameter carbon filaments grown catalytically from carbonaceous gases are reviewed. These relate\\u000a to structural applications, electromagnetic interference shielding, electromagnetic reflection, surface electrical conduction,\\u000a DC electrical conduction, field emission, electrochemical applications, thermal conduction, strain sensors, porous carbons\\u000a and catalyst supports.

  16. Spatial evolution of multiple filaments in air induced by femtosecond laser pulses

    Microsoft Academic Search

    Zuo-Qiang Hao; Jie Zhang; Xin Lu; Ting-Ting Xi; Yu-Tong Li; Xiao-Hui Yuan; Zhi-Yuan Zheng; Zhao-Hua Wang; Wei-Jun Ling; Zhi-Yi Wei

    2006-01-01

    The spatial evolution of plasma filaments in air induced by femtosecond laser pulses is investigated experimentally. Several major filaments and small scaled additional filaments are detected in the plasma channel. The complicated interaction process of filaments as splitting, fusion and spreading is observed. The major filaments propagate stably, and the small scaled additional filaments can be attracted to the major

  17. Production, characterization, and modeling of mineral filled polypropylene filaments

    NASA Astrophysics Data System (ADS)

    George, Brian Robert

    1999-11-01

    This research produced mineral filled polypropylene filaments using a variety of fillers, characterized these filaments, and attempted to model their mechanical properties with current composite models. Also, these filaments were compared with bone to determine if they are suitable for modeling the mechanical properties of bone. Fillers used consist of wollastonite, talc, calcium carbonate, titanium dioxide, and hydroxyapatite. Fillers and polypropylene chips were combined and extruded into rods with the use of a mixer. The rods were chipped up and then formed into filaments through melt extrusion utilizing a piston extruder. Filaments with volume fractions of filler of 0.05, 0.10, 0.15, and 0.20 were produced. Additionally, some methods of trying to improve the properties of these filaments were attempted, but did not result in any significant property improvements. The fillers and filaments were visually characterized with a scanning electron microscope. Cross-sections, filament outer surfaces, fracture surfaces, and longitudinal cut open surfaces were viewed in this manner. Those filaments with anisotropic filler had some oriented filler particles, while all filaments suffered from poor adhesion between the polypropylene and the filler as well as agglomerations of filler particles. Twenty specimens of each filament were tensile tested and the average tenacity, strain, and modulus were calculated. Filaments containing talc, talc and wollastonite, titanium dioxide, or hydroxyapatite suffered from a drastic transition from ductile to brittle with the addition of 0.05 volume fraction of filler. This is evidenced by the sharp decrease in strain at this volume fraction of filler when compared to the strain of the unfilled polypropylene filament. Additionally, these same filaments suffered a sharp decrease in tenacity at the same volume fraction. These instant decreases are attributed to the agglomerations of filler in the filament. Generally, the modulus of the filaments increased with the increase in concentration of filler. The tensile tenacity, strain, and modulus were modeled with current composite models for particulate filled composites. The tenacity and strain models did not accurately predict the properties of the filaments, while the modulus models were more accurate, perhaps because the agglomerations of filler did not affect the modulus as much as it affected the tenacity and strain of the filaments. Production, characterization, and modeling of these filaments indicates that there are many areas for improvements, such as improved mixing of the filler and polypropylene, increased adhesion between matrix and filler, and decreased agglomerations of filler. Mechanically, these filaments can not match the properties of bone. However, they do have many structural similarities at the micro-mechanical level, so with some improvements in properties these filaments may be suitable models for modeling bone behavior.

  18. 2002 SPS MACHINE STATISTICS

    E-print Network

    Desforges, B; CERN. Geneva. SPS and LHC Division

    2002-01-01

    2002 SPS MACHINE STATISTICS Fixed Target Periods with Protons (comments on machine operation, tables and diagrams, comparative tables and diagrams) Fixed Target Periods with Ions (comments on machine operation, tables and diagrams, comparative tables and diagrams)

  19. Wind Energy

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students learn about wind energy by making a pinwheel to model a wind turbine. Just like engineers, they decide where and how their turbine works best by testing it in different areas of the playground.

  20. A double-sided linear primary permanent magnet vernier machine.

    PubMed

    Du, Yi; Zou, Chunhua; Liu, Xianxing

    2015-01-01

    The purpose of this paper is to present a new double-sided linear primary permanent magnet (PM) vernier (DSLPPMV) machine, which can offer high thrust force, low detent force, and improved power factor. Both PMs and windings of the proposed machine are on the short translator, while the long stator is designed as a double-sided simple iron core with salient teeth so that it is very robust to transmit high thrust force. The key of this new machine is the introduction of double stator and the elimination of translator yoke, so that the inductance and the volume of the machine can be reduced. Hence, the proposed machine offers improved power factor and thrust force density. The electromagnetic performances of the proposed machine are analyzed including flux, no-load EMF, thrust force density, and inductance. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed. PMID:25874250

  1. Mind & Machine

    NSDL National Science Digital Library

    Dunn, Ashley.

    Mind & Machine is a weekly column provided by Ashley Dunn for the New York Times Cybertimes that discusses topics related to computing, technology, and the Internet. Recent columns have addressed the topics of the development of Internet telephony, possible futures of user interfaces, the history of technology and standards, and the Internet as a vehicle for community. Articles are well written, opinionated, and thought provoking. Mr. Dunn is a free lance writer who has written for such papers as the New York Times, the Los Angeles Times, the Seattle Post-Intelligencer, and the South China Morning Post. Note that the site is available only upon registration and is free of charge only in the US.

  2. Wind Whispers

    NSDL National Science Digital Library

    The Advanced Technology Environmental and Energy Center (ATEEC) provides this presentation on the career and technical aspects of wind energy. In addition to discussing careers in wind, the presentation covers the siting of wind turbines and some electricity basics. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

  3. Entrainment process at the base of the upper ocean layer in an upwelling filament area

    NASA Astrophysics Data System (ADS)

    Estrada-Allis, Sheila; Rodríguez-Santana, Ángel

    2014-05-01

    Entrainment is responsible for the deepening of the mixed layer and controls the transport of momentum, heat, salinity and nutrients across the interface between the turbulent mixed layer and non-turbulent layer below. This process, which is not yet well understood, can be mechanically forced by wind stirring and buoyancy forced through vertical heat fluxes. In strongly dynamical areas such as eastern boundary upwelling systems and their associated filaments, entrainment rates can also be influenced by vertical shear at the base of the mixed layer that may results from advected baroclinic instabilities. We investigate these processes in the Northwest African upwelling region and Cape Ghir filament using CTD, XBT, ADCP, a meteorological station on board for the wind data and heat flux measurements taken during October 2010, as well as one of the first microturbulent profile (TurboMAP) measurements taken in this area in order to obtain the TKE dissipation rate. We find that buoyancy production dominates over the wind induced mixing in the mixed layer of this region as indicate the Monin Obukhov length scale. To determine entrainment rates we compare four parameterizations based on the turbulent kinetic energy (TKE) balance and one based on the relation of the bulk Richardson number. Although there is no clear consensus between these four parameterizations, they provide evidence that vertical shear at the base of the mixed layer acts to enhance the entrainment rate, especially at stations effected by the upwelling filament or mesoscalar structures. We further compare the measured TKE dissipation rates to those parameterized of Gaspar (1988) and Deardorff (1983). Moreover, some relevant aspect relative to the study of turbulent process in the upper ocean layer, such as the choice of an algorithm or criteria to find the mixed layer depth and the difference between mixing and mixed layer are addressed. This work was funded by Spanish Government (PROMECA: CTM2008-04057/MAR and CTM2009-06993-E/MAR).

  4. A method for dynamic simulation of air-gap eccentricity in induction machines

    Microsoft Academic Search

    Hamid A. Toliyat; Mohammed S. Arefeen; Alexander G. Parlos

    1996-01-01

    In this paper, a method is proposed which enables the simulation of the air-gap eccentricity in induction machines. The method is based on the coupled magnetic circuit approach. The model is derived by means of winding functions, and no symmetry in windings layout is assumed. The parameters of the model are calculated directly from the geometry and winding layout of

  5. Going with the wind

    NASA Astrophysics Data System (ADS)

    Nesbit, W.; Demeo, E.; Goodman, F., Jr.

    1980-03-01

    The current status of wind generation of electricity is surveyed, noting that extracting electric power from such an abundant and inconsistent source requires the correct size, a reliable machine, and power system flexibility to adapt to the air stream. Attention is given to currently operating installations in New Mexico, North Carolina, Puerto Rico, and Rhode Island. Also discussed is the breadth of the federal program including NASA work for the DOE such as the 2.5 MW MOD-2, as well as Sandia work on Darreius design of vertical axis turbines. Other topics examined include siting considerations, private efforts, the depth of analysis required, and the establishing of utility requirements.

  6. Warpage prediction and elimination in filament-wound and fiber-placed composite shells

    NASA Astrophysics Data System (ADS)

    Meink, Troy Edward

    Filament winding and fiber placement are becoming common manufacturing processes throughout the aerospace industry for both launch vehicle and aircraft structures. The promise of significant weight reduction, compared to metallic structures, along with the advantages of automation, including reduced cost and increased quality control, make these attractive structural solutions. Recent demonstrations include: the Combined Experiments (CEP) sub-orbital demonstration flight, Boeing's Sea Launch orbital vehicle, and the Beach Starship. These vehicles employed filament winding or fiber placement manufacturing processes and substantiated large performance gains. However, as with many new technology development programs unforeseen complications often arise. In filament winding the tooling is generally in the form of a plug that has the composite fibers filament wound or fiber placed on the outer surface. Once the parts are released from the tooling they can demonstrate significant warpage. In many cases this warpage is large enough to make the part unusable. As the aerospace industry develops the need for larger composite structures with both the requirements of high performance and reduced manufacturing cost, understanding and controlling part warpage becomes an ever increasing necessity. This research has identified the residual stresses responsible for the large distortions. It will be shown that the stresses develop during manufacturing and result from cure consolidation. The magnitude is dependent on manufacturing parameters including cure pressure, winding tension, and material characteristics (i.e., pre-preg fiber volume fraction, resin viscosity, etc.). In this dissertation a systematic procedure, or methodology, is developed to eliminate the processing induced warpage. This is accomplished by first developing a through-thickness strain model based on fiber/resin cure consolidation and tooling thermal expansions. The strain model is then integrated with classical laminate theory and solutions for predicting and eliminating warpage obtained. The warpage elimination is accomplished by developing manufacturing tension control techniques that reduce and alter the residual stress profile to eliminate stress couples. The accuracy of the warpage prediction and elimination techniques are verified with experimental procedures. It was found that the predictions were accurate and the warpage could be reduced and eliminated in most cases.

  7. Transition from linear- to nonlinear-focusing regime in filamentation

    PubMed Central

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

    2014-01-01

    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

  8. Ultraminiature broadband light source with spiral shaped filament

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L. (Inventor); Collura, Joseph S. (Inventor); Helvajian, Henry (Inventor); Pocha, Michael D. (Inventor); Meyer, Glenn A. (Inventor); McConaghy, Charles F. (Inventor); Olsen, Barry L. (Inventor); Hansen, William W (Inventor)

    2012-01-01

    An ultraminiature light source using a double-spiral shaped tungsten filament includes end contact portions which are separated to allow for radial and length-wise unwinding of the spiral. The double-spiral filament is spaced relatively far apart at the end portions thereof so that contact between portions of the filament upon expansion is avoided. The light source is made by fabricating a double-spiral ultraminiature tungsten filament from tungsten foil and housing the filament in a ceramic package having a reflective bottom and a well wherein the filament is suspended. A vacuum furnace brazing process attaches the filament to contacts of the ceramic package. Finally, a cover with a transparent window is attached onto the top of the ceramic package by solder reflow in a second vacuum furnace process to form a complete hermetically sealed package.

  9. Transition from linear- to nonlinear-focusing regime in filamentation.

    PubMed

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

    2014-01-01

    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

  10. A Comparison Study of an Active Region Eruptive Filament and a Neighboring Non-Eruptive Filament

    NASA Astrophysics Data System (ADS)

    Wu, S. T.; Jiang, C.; Feng, X. S.; Hu, Q.

    2014-12-01

    We perform a comparison study of an eruptive filament in the core region of AR 11283 and a nearby non-eruptive filament. The coronal magnetic field supporting these two filaments is extrapolated using our data-driven CESE-MHD-NLFFF code (Jiang et al. 2013, Jiang etal. 2014), which presents two magnetic flux ropes (FRs) in the same extrapolation box. The eruptive FR contains a bald-patch separatrix surface (BPSS) spatially co-aligned very well with a pre-eruption EUV sigmoid, which is consistent with the BPSS model for the coronal sigmoids. The numerically reproduced magnetic dips of the FRs match observations of the filaments strikingly well, which supports strongly the FR-dip model for filaments. The FR that supports the AR eruptive filament is much smaller (with a length of 3 Mm) compared with the large-scale FR holding the quiescent filament (with a length of 30 Mm). But the AR eruptive FR contains most of the magnetic free energy in the extrapolation box and holds a much higher magnetic energy density than the quiescent FR, because it resides along the main polarity inversion line (PIL) around sunspots with strong magnetic shear. Both the FRs are weakly twisted and cannot trigger kink instability. The AR eruptive FR is unstable because its axis reaches above a critical height for torus instability (TI), at which the overlying closed arcades can no longer confine the FR stably. To the contrary, the quiescent FR is firmly held down by its overlying field, as its axis apex is far below the TI threshold height. (This work is partially supported by NSF AGS-1153323 and 1062050)

  11. Machine musicianship

    NASA Astrophysics Data System (ADS)

    Rowe, Robert

    2002-05-01

    The training of musicians begins by teaching basic musical concepts, a collection of knowledge commonly known as musicianship. Computer programs designed to implement musical skills (e.g., to make sense of what they hear, perform music expressively, or compose convincing pieces) can similarly benefit from access to a fundamental level of musicianship. Recent research in music cognition, artificial intelligence, and music theory has produced a repertoire of techniques that can make the behavior of computer programs more musical. Many of these were presented in a recently published book/CD-ROM entitled Machine Musicianship. For use in interactive music systems, we are interested in those which are fast enough to run in real time and that need only make reference to the material as it appears in sequence. This talk will review several applications that are able to identify the tonal center of musical material during performance. Beyond this specific task, the design of real-time algorithmic listening through the concurrent operation of several connected analyzers is examined. The presentation includes discussion of a library of C++ objects that can be combined to perform interactive listening and a demonstration of their capability.

  12. A new wind energy conversion system

    NASA Technical Reports Server (NTRS)

    Smetana, F. O.

    1975-01-01

    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.

  13. The actin filament severing protein actophorin promotes the formation of rigid bundles of actin filaments crosslinked with alpha-actinin

    PubMed Central

    1991-01-01

    The actin filament severing protein, Acanthamoeba actophorin, decreases the viscosity of actin filaments, but increases the stiffness and viscosity of mixtures of actin filaments and the crosslinking protein alpha-actinin. The explanation of this paradox is that in the presence of both the severing protein and crosslinker the actin filaments aggregate into an interlocking meshwork of bundles large enough to be visualized by light microscopy. The size of these bundles depends on the size of the containing vessel. The actin filaments in these bundles are tightly packed in some areas while in others they are more disperse. The bundles form a continuous reticulum that fills the container, since the filaments from a particular bundle may interdigitate with filaments from other bundles at points where they intersect. The same phenomena are seen when rabbit muscle aldolase rather than alpha-actinin is used as the crosslinker. We propose that actophorin promotes bundling by shortening the actin filaments enough to allow them to rotate into positions favorable for lateral interactions with each other via alpha-actinin. The network of bundles is more rigid and less thixotropic than the corresponding network of single actin filaments linked by alpha-actinin. One explanation may be that alpha-actinin (or aldolase) normally in rapid equilibria with actin filaments may become trapped between the filaments increasing the effective concentration of the crosslinker. PMID:1757466

  14. Three Dimension Filamentous Human Cardiac Tissue Model

    PubMed Central

    Ma, Zhen; Koo, Sangmo; Finnegan, Micaela A.; Loskill, Peter; Huebsch, Nathaniel; Marks, Natalie C.; Conklin, Bruce R.; Grigoropoulos, Costas P.; Healy, Kevin E.

    2013-01-01

    A human in vitro cardiac tissue model would be a significant advancement for understanding, studying, and developing new strategies for treating cardiac arrhythmias and related cardiovascular diseases. We developed an in vitro model of three-dimensional (3D) human cardiac tissue by populating synthetic filamentous matrices with cardiomyocytes derived from healthy wild-type volunteer (WT) and patient-specific long QT syndrome type 3 (LQT3) induced pluripotent stem cells (iPS-CMs) to mimic the condensed and aligned human ventricular myocardium. Using such a highly controllable cardiac model, we studied the contractility malfunctions associated with the electrophysiological consequences of LQT3 and their response to a panel of drugs. By varying the stiffness of filamentous matrices, LQT3 iPS-CMs exhibited different level of contractility abnormality and susceptibility to drug-induced cardiotoxicity. PMID:24268663

  15. Influence of multiple ionization in laser filamentation

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  16. Theory of swimming filaments in viscoelastic media

    NASA Astrophysics Data System (ADS)

    Fu, Henry

    2008-03-01

    Microorganisms often encounter and must move through complex media. What aspects of propulsion are altered when swimming in viscoelastic gels and fluids? Motivated by the swimming of sperm through the mucus of the female mammalian reproductive tract, we examine the swimming of filaments in nonlinearly viscoelastic fluids. We obtain the swimming velocity and hydrodynamic force exerted on an infinitely long cylinder with prescribed beating pattern. We apply these results to study the swimming of a simplified sliding-filament model for a sperm flagellum. Viscoelasticity tends to decrease swimming speed. The viscoelastic response of the fluid can change the shapes of beating patterns, and changes in the beating patterns can even lead to reversal of the swimming direction.

  17. SWAYING THREADS OF A SOLAR FILAMENT

    SciTech Connect

    Lin, Y.; Engvold, O.; Langangen, Oe.; Rouppe van der Voort, L. H. M. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway); Soler, R.; Ballester, J. L.; Oliver, R. [Departament de FIsica, Universitat de les Illes Balears, E-07122, Palma de Mallorca (Spain)

    2009-10-10

    From recent high-resolution observations obtained with the Swedish 1 m Solar Telescope in La Palma, we detect swaying motions of individual filament threads in the plane of the sky. The oscillatory characters of these motions are comparable with oscillatory Doppler signals obtained from corresponding filament threads. Simultaneous recordings of motions in the line of sight and in the plane of the sky give information about the orientation of the oscillatory plane. These oscillations are interpreted in the context of the magnetohydrodynamic (MHD) theory. Kink MHD waves supported by the thread body are proposed as an explanation of the observed thread oscillations. On the basis of this interpretation and by means of seismological arguments, we give an estimation of the thread Alfven speed and magnetic field strength by means of seismological arguments.

  18. Morphogenesis of filaments growing in flexible confinements

    E-print Network

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

    2014-07-17

    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.

  19. Solar Magnetized "Tornadoes": Relation to Filaments

    E-print Network

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

    2012-01-01

    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...

  20. Viscoelastic response of contractile filament bundles

    E-print Network

    Achim Besser; Julien Colombelli; Ernst H. K. Stelzer; Ulrich S. Schwarz

    2011-02-25

    The actin cytoskeleton of adherent tissue cells often condenses into filament bundles contracted by myosin motors, so-called stress fibers, which play a crucial role in the mechanical interaction of cells with their environment. Stress fibers are usually attached to their environment at the endpoints, but possibly also along their whole length. We introduce a theoretical model for such contractile filament bundles which combines passive viscoelasticity with active contractility. The model equations are solved analytically for two different types of boundary conditions. A free boundary corresponds to stress fiber contraction dynamics after laser surgery and results in good agreement with experimental data. Imposing cyclic varying boundary forces allows us to calculate the complex modulus of a single stress fiber.

  1. Transverse-mode dependence of femtosecond filamentation.

    PubMed

    Song, Zhenming; Zhang, Zhigang; Nakajima, Takashi

    2009-07-20

    We theoretically investigate the transverse-mode dependence of femtosecond filamentation in Ar gas. Three different transverse modes, Bessel, Gaussian, and Laguerre modes, are considered for incident laser pulses. By solving the extended nonlinear Schrödinger equation coupled with the electron density equation, we find that the lengths of the filament and the plasma channel induced by the Bessel incident beam is much longer than the other transverse modes with the same peak intensity, pulse duration, and beam diameter. Moreover we find that the temporal profile of the pulse with the Bessel incident mode is nearly undistorted during the propagation. Since the pulse energy that the Bessel beam can carry is more than one order of magnitude larger than the other modes for the same peak intensity, pulse duration, and beam diameter, the Bessel beam can be a very powerful tool in ultrafast nonlinear optics involving propagation in a Kerr medium. PMID:19654624

  2. Large Wind Turbine Design Characteristics and R and D Requirements

    NASA Technical Reports Server (NTRS)

    Lieblein, S. (editor)

    1979-01-01

    Detailed technical presentations on large wind turbine research and development activities sponsored by public and private organizations are presented. Both horizontal and vertical axis machines are considered with emphasis on their structural design.

  3. Machine Shop Lathes.

    ERIC Educational Resources Information Center

    Dunn, James

    This guide, the second in a series of five machine shop curriculum manuals, was designed for use in machine shop courses in Oklahoma. The purpose of the manual is to equip students with basic knowledge and skills that will enable them to enter the machine trade at the machine-operator level. The curriculum is designed so that it can be used in…

  4. The evolving structure of an upwelling filament

    Microsoft Academic Search

    Pierre Flament; Laurence Armi; Libe Washburn

    1985-01-01

    The evolution of an upwelling filament was studied over a 2-week period by using satellite infrared images, and its thermohaline structure was mapped in situ. The surface velocity field consisted of a large meander extending offshore for at least 300 km. The northern branch was ~40 km wide, flowing offshore at a peak velocity of 0.55 m\\/s; the southern branch

  5. The properties of galaxies in supercluster filaments

    NASA Astrophysics Data System (ADS)

    Porter, Scott C.

    2007-10-01

    Superclusters appear as large-scale structures in the form of a network of filaments, and can be up to 100h-1100 Mpc in extent. In this dissertation, we investigate in detail the spatial structure of the three richest superclusters of galaxies closer to us then z=0.1. We investigate the rate of star formation in galaxies at various positions among the filaments and clusters in the Pisces-Cetus Supercluster. We use an index of star formation derived from a principal component analysis of optical spectral. We have shown that galaxies which are members of these filaments, show a steady decline in star formation rate, from the periphery of a cluster, into the cluster core. However, on top of this trend, we find a nearby instantaneous enhancement of the rate of star formation at ~3h-170 Mpc from its centre. We conclude that the most likely reason for this sudden enhancement in star formation rate is galaxy-galaxy harassment. Further work shows that the enhancement in star formation occurs mainly in the in falling dwarf galaxies (-20 < MB < -17.5) and that there is little evidence that the tidal effect of the dark matter haloes of the clusters is responsible for the enhanced star formation. The results of an analysis performed on a larger ensemble of 52 filaments were consistent with those from our smaller sample drawn from the Pisces-Cetus supercluster. We conclude this study with the analysis of a sample of spectra from the 6dF redshift survey. In the absence of spectrophotometric calibration, for these galaxies we were only able to obtain an uncalibrated star formation rate, but we could examine the effect of correction due to dust extinction, and could separate the starforming galaxies from the active galactic nuclei. From our small sample, there was interesting evidence of enhanced star formation in galaxies at similar distances from the centres of the clusters in the Shapley Supercluster.

  6. Turbulent Boundary Layers over Filamentous Algae

    Microsoft Academic Search

    Michael P. Schultz

    1999-01-01

    Turbulent boundary layer measurements have been made on surfaces covered with filamentous marine algae. These experiments were conducted in a closed return water tunnel using a two-component, laser Doppler velocimeter (LDV). The axial and wall-normal turbulence intensities and Reynolds shear stress are compared with flows over smooth and conventional k-type rough walls. The results indicate that profiles of these turbulence

  7. DOE/NASA Lewis large-wind-turbine program

    SciTech Connect

    Thomas, R.L.

    1982-01-01

    There are several ongoing large wind system development project; ots directed toward meeting the technology requirements for utility applications. First generation tehcnology machines (Mod-0A and Mod-1) and second generation machines (Mod-2) are in opoeration at selected utility sites. Third generation technology machines (Mod-5) are in the design phase and are scheduled for initial operation in 1984 if project funding is continued. An overview of the large wind turbine activities managed by NASA Lewis is provided. These activities include results from the first and second generation field machines (Mod-0A, 01, 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).

  8. Wind turbine

    SciTech Connect

    Yeoman, D.R.

    1989-07-25

    This patent describes a wind turbine. It comprises: a vertical axis rotor assembly coupled to a rotatable drive shaft for driving electrical power generating means; first wind deflector means for initially reflecting wind current into the rotor assembly; second wind deflector means to redirect the initially deflected wind current into the rotor assembly; and mounting means for mounting the first and second wind deflector means in the normal positions. The mounting means including an outer shaft through which the drive shaft extends and which is normally fixed with respect thereto. The outer shaft having at least one lower groove winding in one of a left-hand or right-hand direction, at least one lower groove constituting a first lower groove set, and at least one upper groove winding in the other of the left-hand or right-hand direction, at least one upper groove constituting a second upper groove set, and first lower and second upper connector rings coupled to the first and second wind deflector means respectively, and mounted on the outer shaft proximate to the first and second groove sets respectively. The first and second connector rings including guide means cooperating with at least one groove of the first and second groove sets respectively. The mounting means allowing at least one of the first and second wind deflector means to automatically move relative to each other and from its respective normal position when the velocity of the wind current exceeds a first predetermined value to increase the inter-deflector spacing and causing at least one of the first and second wind deflector means to automatically return to its respective normal position when the velocity of the wind current diminishes to a value below the first predetermined value.

  9. Hot filament CVD of boron nitride films

    DOEpatents

    Rye, Robert R. (Albuquerque, NM)

    1992-01-01

    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.

  10. A filament of energetic particles near the high-latitude dawn magnetopause

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Williams, D. J.; Mcentire, R. W.; Christon, S. P.; Jacquey, C.; Angelopoulos, V.; Yamamoto, T.; Kokubun, S.; Frank, L. A.; Ackerson, K. L.

    1994-01-01

    The Geotail satelite detected a filament of tailward-streaming energetic particles spatially separated from the boundary layer of energetic particles at the high-latitude dawn magnetopause at a downstream distance of approximately 80 R(sub E) on October 27, 1992. During this event, the composition and charge states of energetic ions at energies above approximately 10 keV show significant intermix of ions from solar wind and ionospheric sources. Detailed analysis leads to the deduction that the filament was moving southward towards the neutral sheet at an average speed of approximately 80 km/s, implying an average duskward electric field of approximately 1 mV/m. Its north-south dimension was approximately 1 R(sub E) and it was associated with an earthward directed field-aligned current of approximately 5 mA/m. The filament was separated from the energetic particle boundary layer straddling the magnetopause by approximately 0.8 R(sub E) and was inferred to be detached from the boundary layer at downstream distance beyond approximately 70 R(sub E) in the distant tail.

  11. Geometric modeling and electromagnetic analysis of electrical windings for pulsed alternators

    Microsoft Academic Search

    G. A. Wedeking

    2005-01-01

    Pulsed alternators are state-of-the-art machines that require analytical design tools with a high level of fidelity. To meet the design needs, accurate modeling and analysis methods of the electrical windings of the machines have had to be developed. This paper will present a technique for creating accurate geometric models of racetrack style electrical windings, as well as a means of

  12. Geometric modeling and EM analysis of electrical windings for pulsed alternators

    Microsoft Academic Search

    G. A. Wedeking

    2004-01-01

    Pulsed alternators are state-of-the-art machines that require analytical design tools with a high level of fidelity. To meet the design needs, accurate modeling and analysis methods of the electrical windings of the machines have had to be developed. This paper will present a technique for creating accurate geometric models of racetrack style electrical windings, as well as a means of

  13. Analysis of Optimal Stator Concentric Winding Patterns University of Wisconsin-Madison

    E-print Network

    Lipo, Thomas

    #12;1 Abstract -- Most small induction motors in current use employ concentric windings which have Motive Force (MMF) harmonics of electrical machine created by the stator concentric windings for uniform air-gap machines. By evaluating the harmonic property of the synthesized three phase air gap MMF

  14. Grid Operation and Coordination with Wind -2 1.0 Introduction

    E-print Network

    McCalley, James D.

    ), will generally differ from the wind speed for turbine k at time t2, vk(t2), where t2>t1. For fixed speed machines2 cause variations in electric power out of the wind generator. Double-fed induction generators that this variability is less volatile than fixed-speed machines. For a single turbine, this variability depends

  15. Validity of using average diameter for determination of tensile strength and Weibull modulus of ceramic filaments

    SciTech Connect

    Petry, M.D.; Mah, T.I. [UES Inc., Dayton, OH (United States); Kerans, R.J. [Materials Directorate, Wright-Patterson AFB, OH (United States). Wright Lab.

    1997-10-01

    Strengths and Weibull moduli for alumina/yttrium aluminum garnet eutectic (AYE) filaments and for Si-C-O (Nicalon) filaments were calculated using measured and average filament diameters. The strengths agreed closely. Thus an average filament diameter could be used instead of the measured filament diameter in calculating strengths. The Weibull modulus obtained from an average filament diameter approximates the Weibull modulus obtained using the measured filament diameter.

  16. Zooplankton community pattern associated with a California Current cold filament

    NASA Astrophysics Data System (ADS)

    Mackas, David L.; Washburn, Libe; Smith, Sharon L.

    1991-08-01

    In July 1988 we sampled upper layer zooplankton distributions in and around a major cold filament located off Point Arena, California. Average zooplankton biomass levels declined inshore to offshore, but relatively high levels extended seaward along the cool side of the filament jet. A series of transverse station lines shows strong shifts in community composition across the axis of the filament. The cross-filament compositional sequence was recognizably similar along each line, giving an impression (supported by cluster analysis and along-flow versus cross-flow spatial autocorrelation) of banding parallel to the filament axis. The "standard" sequence was characterized by local maxima of Dolioletta gegenbauri in nonfilament waters to the south and east, Euphausia pacifica along the southeast margin of the filament, Eucalanus californicus and euphausiid larvae within the cool core of the filament and extending partway across the strong seaward jet on the north and west margin of the filament, and heteropod larvae, chaetognaths, Dolioletta, and a mixture of small copepods (including several with southern and offshore faunal affinities) along the warm side of the jet and extending into nonfilament waters to the north and west. A "core" group of samples characterized by high abundance of Eucalanus matched the trajectories of drifters released at the upstream end of the filament. Both crossed geopotential anomaly contours (to larger ?) as they moved out the filament, suggesting a cross-jet component of motion.

  17. Microtubule-dependent transport and dynamics of vimentin intermediate filaments

    PubMed Central

    Hookway, Caroline; Ding, Liya; Davidson, Michael W.; Rappoport, Joshua Z.; Danuser, Gaudenz; Gelfand, Vladimir I.

    2015-01-01

    We studied two aspects of vimentin intermediate filament dynamics—transport of filaments and subunit exchange. We observed transport of long filaments in the periphery of cells using live-cell structured illumination microscopy. We studied filament transport elsewhere in cells using a photoconvertible-vimentin probe and total internal reflection microscopy. We found that filaments were rapidly transported along linear tracks in both anterograde and retrograde directions. Filament transport was microtubule dependent but independent of microtubule polymerization and/or an interaction with the plus end–binding protein APC. We also studied subunit exchange in filaments by long-term imaging after photoconversion. We found that converted vimentin remained in small clusters along the length of filaments rather than redistributing uniformly throughout the network, even in cells that divided after photoconversion. These data show that vimentin filaments do not depolymerize into individual subunits; they recompose by severing and reannealing. Together these results show that vimentin filaments are very dynamic and that their transport is required for network maintenance. PMID:25717187

  18. Filamentous structures in skeletal muscle: anchors for the subsarcolemmal space.

    PubMed

    Khairani, Astrid Feinisa; Tajika, Yuki; Takahashi, Maiko; Ueno, Hitoshi; Murakami, Tohru; Soenggono, Arifin; Yorifuji, Hiroshi

    2015-03-01

    In skeletal muscle fibers, intermediate filaments and actin filaments provide structural support to the myofibrils and the sarcolemma. For many years, it was poorly understood from ultrastructural observations that how these filamentous structures were kept anchored. The present study was conducted to determine the architecture of filamentous anchoring structures in the subsarcolemmal space and the intermyofibrils. The diaphragms (Dp) of adult wild type and mdx mice (mdx is a model for Duchenne muscular dystrophy) were subjected to tension applied perpendicular to the long axis of the muscle fibers, with or without treatment with 1% Triton X-100 or 0.03% saponin. These experiments were conducted to confirm the presence and integrity of the filamentous anchoring structures. Transmission electron microscopy revealed that these structures provide firm transverse connections between the sarcolemma and peripheral myofibrils. Most of the filamentous structures appeared to be inserted into subsarcolemmal densities, forming anchoring connections between the sarcolemma and peripheral myofibrils. In some cases, actin filaments were found to run longitudinally in the subsarcolemmal space to connect to the sarcolemma or in some cases to connect to the intermyofibrils as elongated thin filaments. These filamentous anchoring structures were less common in the mdx Dp. Our data suggest that the transverse and longitudinal filamentous structures form an anchoring system in the subsarcolemmal space and the intermyofibrils. PMID:24519712

  19. Synthesis of high performance PM motors with concentrated windings

    Microsoft Academic Search

    Jéröme Cros; Philippe Viarouge

    2002-01-01

    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

  20. A modular permanent magnet brushless generator for wind power

    Microsoft Academic Search

    Wei Hua; Gan Zhang; Ming Cheng

    2010-01-01

    In this paper, a permanent magnet brushless machine for wind power with novel concentrated windings, is introduced, in which the special combination of stator slots\\/rotor poles is employed, resulting in high power density and low cogging torque. The distinct topology and operation principle are analyzed by using a 3-phase 24\\/22-pole prototyped machine as an example. Based on finite element method,

  1. Geometry of flexible filament cohesion: Better contact through twist?

    E-print Network

    Luis Cajamarca; Gregory M. Grason

    2014-11-03

    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.

  2. Wind turbine

    SciTech Connect

    Yeoman, D.R.

    1987-03-24

    A wind turbine is described comprising: a vertical axis rotor assembly coupled to a rotatable drive shaft for driving electrical power generating means; first wind deflector means mounted on the wind turbine normally positioned generally upwind and to one side of the rotor assembly for initially deflecting wind current into the rotor assembly and second wind deflector means mounted on the wind turbine normally positioned on another side of the rotor assembly to redirect the initially deflected wind current into the rotor assembly. The first and second wind deflector means are normally spaced from each other by a certain inter-deflector spacing; mounting means for mounting the first and second wind deflector means in the normal positions, the mounting means including an outer shaft through which the drive shaft extends and which is normally fixed with respect thereto. The outer shaft has an upwardly facing circumferentially extending shoulder formed therein including a first shoulder portion extending around a major portion of the circumference of the outer shaft and a pair of upwardly sloping portions which reet at an apex.

  3. Low cost composite materials for wind energy conversion systems

    NASA Astrophysics Data System (ADS)

    Weingart, O.

    1980-06-01

    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).

  4. Development of vertical axis wind turbines

    Microsoft Academic Search

    P N Shankar

    1979-01-01

    This paper summarises the work done at the National Aeronautical Laboratory (NAL) between 1975 and 1977 on the development\\u000a of vertical axis wind turbines based on the Darrieus rotor. On the analytical side, a performance analysis was developed which\\u000a permits the estimation of the characteristics of such machines. A 5 m high wind turbine using curved wooden blades was designed,

  5. Turbogenerator end winding leakage inductance calculation using a 3-D analytical approach based on the solution of Neumann integrals

    Microsoft Academic Search

    D. Ban; D. Zarko; I. Mandic

    2003-01-01

    An analytical technique that can be effectively used for the calculation of the end winding leakage inductance of a turbogenerator has been presented. It is based on a 3-D geometric model of the end winding region in which each coil is modeled as a set of serially connected straight filaments. The calculation of the mutual inductance of the end coils

  6. THE DOUBLE ARRAY OF FILAMENTS IN CROSS-STRIATED MUSCLE

    PubMed Central

    Huxley, H. E.

    1957-01-01

    The conditions under which one might expect to see the secondary filaments (if they exist) in longitudinal sections of striated muscle, are discussed. It is shown that these conditions were not satisfied in previously published works for the sections were too thick. When suitably thin sections are examined, the secondary filaments can be seen perfectly easily. It is also possible to see clearly other details of the structure, notably the cross-bridges between primary and secondary filaments, and the tapering of the primary filaments at their ends. The arrangement of the filaments and the changes associated with contraction and with stretch are identical to those already deduced from previous observations and described in terms of the interdigitating filament model in previous papers. There are therefore excellent grounds for believing that this model is correct. The alternative models which have been proposed appear to be incompatible both with the present observations and with much of the other available evidence. PMID:13475381

  7. Microwave guiding in air along single femtosecond laser filament

    SciTech Connect

    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

    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.

  8. A FILAMENT ERUPTION ON 2010 OCTOBER 21 FROM THREE VIEWPOINTS

    SciTech Connect

    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

    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.

  9. Hybrid Quantum Cloning Machine

    E-print Network

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

    2007-06-14

    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} $

  10. Control of lasing filament arrays in nonlinear liquid media

    Microsoft Academic Search

    L. Guyon; K. M. Hajek; F. Courvoisier; V. Boutou; R. Nuter; A. Vinçotte; S. Champeaux; L. Bergé; J.-P. Wolf

    2008-01-01

    Multiple filamentation in a high concentration solution of coumarin 153 in ethanol is studied. It is shown that the output\\u000a filament pattern may be controlled by placing diffractive elements (circular aperture, edge) in the input beam path. These\\u000a filaments are formed in highly reproducible arrays along diffraction maxima corresponding to the element used. Experimental\\u000a results are supported by numerical simulations.

  11. Developments in hot-filament metal oxide deposition (HFMOD)

    Microsoft Academic Search

    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

    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).

  12. Multiple filamentation of non-uniformly focused ultrashort laser pulses

    Microsoft Academic Search

    Z. Q. Hao; R. Salamé; N. Lascoux; E. Salmon; P. Maioli; J. Kasparian; J.-P. Wolf

    2009-01-01

    We propose the impingement of non-uniform wavefront curvature as a simple way to improve the longitudinal homogeneity of the\\u000a plasma density along filaments generated by ultrashort laser pulses. We characterize multiple filamentation of a multiterawatt\\u000a beam with different wavefront curvatures applied to specific regions in the transverse beam profile. In adequate conditions,\\u000a the filamenting region is more homogeneously ionized, in

  13. A review of UK wind energy activities

    NASA Astrophysics Data System (ADS)

    Musgrove, P. J.

    1982-01-01

    Wind power activities in Great Britain are reviewed, including a brief summary of historical windmill usage and details of developmental efforts in large and small wind turbines. An annual average resource of 5 m/sec at 10 m has been extrapolated to predict an 8-10 m/sec resource at the hub heights of large wind turbines. Initial estimates indicate that at least half of Great Britain's annual electricity consumption can be produced from windpowered generators. The potential of offshore large WECS siting is being examined, although the wind-derived electricity from those regions are projected to cost three times that of land-based operation. Recorded wind patterns with 12-48 hr. duration have indicated that at least 20% penetration into the national grid is acceptable. A test 250 kW machine is being built as a model for a 3.7 MW machine, both intended for installation at Orkney, Scotland. Additionally, construction has begun on a 25-m diameter, vertical axis, variable geometry Musgrove wind turbine. The straight-bladed machine will produce a maximum of 130 kW, and is a prototype of multi-MW offshore units.

  14. Wind power electrical drives for permanent magnet generators — Development in Finland

    Microsoft Academic Search

    Juha J. Pyrhonen; Yulia Alexandrova; R. Scott Semken; Henry Hamalainen

    2012-01-01

    The use of permanent magnets offers freedom in machine design and the highest possible efficiencies for wind power machines. Although full power converters must be used with permanent magnet machines, these converters make it possible to fulfill even the strictest grid codes. If appropriate care is taken in selecting the exact magnetic material composition, Neodymium-Iron-Boron magnets are compatible with long

  15. Development, Persistence, and Variability of Upwelling Filaments off the Ariantic Coast of the Iberian Peninsula

    Microsoft Academic Search

    R. HAYNES; E. D. BARTON; I. PR

    The filaments appear first as bulges in the upwelling front. These bulges grow offshore to form filaments that reach their maximum length (200-250 kin) in September. The lengths of the filaments gradually decreuntil the filaments become relatively rare in late October. Typically, five or six fully developed filaments ate observed off the Iberian Peninsula late in the upwelling season. Most

  16. Improving the electrochemical performance of carbon filaments by solvent cleansing

    SciTech Connect

    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

    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.

  17. The two types of flare associated filament eruptions

    NASA Technical Reports Server (NTRS)

    Tang, F.

    1986-01-01

    Using years of high resolution solar footage obtained at Big Bear Solar Observatory flare associated filament eruptions were studied. In addition to the classical type eruption consisting of expansion and breakup, evidence was found of another type where a layer is shed from the filament and erupts while the inversion line filament below (or, what is left of it) remains in place. Both types of eruptions are presented. It is hoped that the new evidence will shed new light on the understanding of the role of filaments in flares.

  18. Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding

    SciTech Connect

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

    2013-01-15

    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.

  19. Evidence for intermediate-like filaments in a heterotrichous ciliate.

    PubMed

    Mohr, M; Ruthmann, A; Eichenlaub-Ritter, U; Kühn, S; Traub, P

    1990-03-01

    In the heterotrichous ciliate Nyctotherus ovalis, a meshwork of 10 nm filaments present in the cell cortex surrounds cytostome and cytoproct and is connected by thin strands to a perinuclear coat. Like intermediate filaments (If) of higher organisms the filaments are insoluble in non-ionic detergent, and paracrystals can be formed after dissolution in 8 M urea. The cross-reactions of these filaments with monoclonal anti-vimentin and anti-cytokeratin antibodies suggest that they share common epitopes with both types of If proteins. PMID:23195973

  20. Where Do Solar Filaments Form?: Consequences for Theoretical Models

    NASA Astrophysics Data System (ADS)

    Mackay, Duncan H.; Gaizauskas, Victor; Yeates, Anthony R.

    2008-03-01

    This paper examines the locations where large, stable solar filaments form relative to magnetic bipoles lying underneath them. The study extends the earlier work of F. Tang to include two additional classification categories for stable filaments and to consider their population during four distinct phases of the solar cycle. With this new classification scheme, results show that over 92% of filaments form in flux distributions that are nonbipolar in nature where the filament lies either fully (79%) or partially (13%) above a polarity inversion line (PIL) external to any single bipole. Filaments that form within a single bipole (traditionally called Type A) are not as common as previously thought. These results are a significant departure from those of F. Tang. Consistency with the earlier work is shown when our data are regrouped to conform to the two-category classification scheme for filaments adopted by F. Tang. We also demonstrate that only filaments that form along the external PIL lying between two bipoles (62% of the full sample, traditionally called Type B) show any form of solar cycle dependence, where their number significantly increases with magnetic activity over the solar cycle. Finally, current observations and theoretical models for the formation of filaments are discussed in the context of the present results. We conclude that key elements in the formation of the majority of filaments considered within this study must be the convergence of magnetic flux resulting in either flux cancellation or coronal reconnection.

  1. Wind energy.

    PubMed

    Leithead, W E

    2007-04-15

    From its rebirth in the early 1980s, the rate of development of wind energy has been dramatic. Today, other than hydropower, it is the most important of the renewable sources of power. The UK Government and the EU Commission have adopted targets for renewable energy generation of 10 and 12% of consumption, respectively. Much of this, by necessity, must be met by wind energy. The US Department of Energy has set a goal of 6% of electricity supply from wind energy by 2020. For this potential to be fully realized, several aspects, related to public acceptance, and technical issues, related to the expected increase in penetration on the electricity network and the current drive towards larger wind turbines, need to be resolved. Nevertheless, these challenges will be met and wind energy will, very likely, become increasingly important over the next two decades. An overview of the technology is presented. PMID:17272245

  2. Mechanism of Actin Filament Bundling by Fascin

    SciTech Connect

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

    2013-03-07

    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.

  3. Modeling of wind farms in the load flow analysis

    Microsoft Academic Search

    A. E. Feijoo; J. Cidras

    2000-01-01

    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

  4. Wind Energy Conversion Systems. A Unit of Instruction.

    ERIC Educational Resources Information Center

    Greenwald, Martin

    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…

  5. A 200kW wind turbine power chain

    Microsoft Academic Search

    Yan Tai Chang; K. W. E. Cheng; Jiongkang Lin

    2009-01-01

    This paper presents a modern configuration of the power chain for a high power wind turbine machine using permanent magnet generator. A test setup is shown and device specifications are described. Advantages of using direct drive generators are also shown. The discussion on the use of SRG is proposed. It provides a low speed solution of the wind turbine power

  6. Plasma planar filament instability and Alfven waves

    E-print Network

    Garcia de Andrade

    2007-03-05

    Inhomogeneous plasmas filaments instabilities are investigated by using the techniques of classical differential geometry of curves where Frenet torsion and curvature describe completely the motion of curves. In our case the Frenet frame changes in time and also depends upon the other coordinates taking into account the inhomogeneity of the plasma. The exponential perturbation method so commonly used to describe cosmological perturbatons is applied to magnetohydrodynamic (MHD) plasma equations to find longitudinal modes describing Alfven waves propagation modes describing plasma waves in the medium. Stability is investigated in the imaginary axis of the spectra of complex frequencies ${\\omega}$ or $Im(\\omega)\

  7. Quantum kinetic theory of the filamentation instability

    E-print Network

    A. Bret; F. Haas

    2011-05-10

    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.

  8. Buckling, Coiling, and Perversions of Viscoelastic Filaments

    NASA Astrophysics Data System (ADS)

    Goriely, Alain; Goldstein, Raymond

    2004-03-01

    Certain species of climbing vines attach themselves to supports through tendrils which develop helicity after attachment. Often, the tendrils develop regions of opposite helix handedness joined by a junction known as a perversion. A key feature of these structures is that during their development they are elastically imprinted with the shape they display, so that removal of the external constraints leaves them in a nearly equilibrium shape. Existing models based on static elasticity theory can not explain this behavior. Here we show that a model of differential growth and viscoelastic relaxation of the intrinsic curvature and torsion of the filament can explain the details of this phenomenon, in basic agreement with experimental observations.

  9. Automated detection of filaments in SDO data

    NASA Astrophysics Data System (ADS)

    Buchlin, É.; Mercier, C.; Engin, S.; Parenti, S.; Vial, J.-C.

    2010-12-01

    Solar eruption can eject billions of tons of plasma to the interplanetary space, with geophysical effects and impacts on human activities. The time constraints for space weather application as well as the huge volume of data that needs to be analyzed, especially since the launch of SDO, imply that the detection of solar filaments and their eruptions must be automated. Most current detection codes use H? data, which are not available frequently enough for these applications. We present a new detection code that we have developed at IAS and that uses the high spatial and temporal-resolution SDO/AIA He II 30.4 nm data.

  10. Dynamic fluctuations of dipolar semiflexible filaments

    NASA Astrophysics Data System (ADS)

    Belovs, M.; C?bers, A.

    2006-02-01

    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.

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

    SciTech Connect

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

    2006-06-01

    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.

  12. Wind Energy Leasing Handbook

    E-print Network

    Balasundaram, Balabhaskar "Baski"

    Wind Energy Leasing Handbook Wind Energy Leasing Handbook E-1033 Oklahoma Cooperative Extension? .................................................................................................................. 24 How has wind been used to generate power in the past?..................................................................................................................... 31 What do wind developers consider in locating wind energy projects

  13. LISP Machine Progress Report

    E-print Network

    Bawden, Alan

    1977-08-01

    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, ...

  14. Infinite Time Turing Machines

    Microsoft Academic Search

    Joel David Hamkins

    2002-01-01

    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.

  15. Proper horizontal photospheric flows in a filament channel

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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

  16. A Correlative Analysis of Actin Filament Assembly, Structure, and Dynamics

    PubMed Central

    Steinmetz, Michel O.; Goldie, Kenneth N.; Aebi, Ueli

    1997-01-01

    The effect of the type of metal ion (i.e., Ca2+, Mg2+, or none) bound to the high-affinity divalent cation binding site (HAS) of actin on filament assembly, structure, and dynamics was investigated in the absence and presence of the mushroom toxin phalloidin. In agreement with earlier reports, we found the polymerization reaction of G-actin into F-actin filaments to be tightly controlled by the type of divalent cation residing in its HAS. Moreover, novel polymerization data are presented indicating that LD, a dimer unproductive by itself, does incorporate into growing F-actin filaments. This observation suggests that during actin filament formation, in addition to the obligatory nucleation– condensation pathway involving UD, a productive filament dimer, a facultative, LD-based pathway is implicated whose abundance strongly depends on the exact polymerization conditions chosen. The “ragged” and “branched” filaments observed during the early stages of assembly represent a hallmark of LD incorporation and might be key to producing an actin meshwork capable of rapidly assembling and disassembling in highly motile cells. Hence, LD incorporation into growing actin filaments might provide an additional level of regulation of actin cytoskeleton dynamics. Regarding the structure and mechanical properties of the F-actin filament at steady state, no significant correlation with the divalent cation residing in its HAS was found. However, compared to native filaments, phalloidin-stabilized filaments were stiffer and yielded subtle but significant structural changes. Together, our data indicate that whereas the G-actin conformation is tightly controlled by the divalent cation in its HAS, the F-actin conformation appears more robust than this variation. Hence, we conclude that the structure and dynamics of the Mg–F-actin moiety within the thin filament are not significantly modulated by the cyclic Ca2+ release as it occurs in muscle contraction to regulate the actomyosin interaction via troponin. PMID:9245786

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

    SciTech Connect

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

    1991-01-01

    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. 11 refs., 12 figs., 4 tabs.

  18. Lebost wind turbine: laboratory tests and data analysis

    Microsoft Academic Search

    M. I. Hoffert; B. A. Rugg

    1978-01-01

    Preliminary aerodynamic torque and power measurements and data analysis are presented for the Lebost Wind Turbine--a recently patented vertical-axis wind energy machine incorporating flow-focusing inlets fixed to a housing shroud surrounding blades rotating normal to the flow. Two laboratory-scale models were constructed, instrumented, and tested in a specially modified section of the NYU 30-m wind tunnel at freestream velocities (U\\/sub

  19. Electronically commutated serial-parallel switching for motor windings

    DOEpatents

    Hsu, John S. (Oak Ridge, TN)

    2012-03-27

    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.

  20. What is Machine Learning? About the Course Example Machine Learning

    E-print Network

    Kjellström, Hedvig

    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

  1. What is Machine Learning? About the Course Example Machine Learning

    E-print Network

    Kjellström, Hedvig

    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

  2. What is Machine Learning? About the Course Example Machine Learning

    E-print Network

    Kjellström, Hedvig

    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

  3. What is Machine Learning? About the Course Example Machine Learning

    E-print Network

    Kjellström, Hedvig

    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

  4. Production of cutinolytic esterase by filamentous bacteria.

    PubMed

    Fett, W F; Wijey, C; Moreau, R A; Osman, S F

    2000-07-01

    Thirty-eight strains of filamentous bacteria, many of which are thermophilic or thermotolerant and commonly found in composts and mouldy fodders, were examined for their ability to produce cutinolytic esterase (cutinase) in culture media supplemented with cutin, suberin or cutin-containing agricultural by-products. Initially, the ability of culture supernatants to hydrolyse the artificial substrate p-nitrophenyl butyrate was determined by spectrophotometric assays. Only one bacterium, Thermoactinomyces vulgaris NRRL B-16117, exhibited cutinolytic esterase production. The enzyme was highly inducible, was repressed by the presence of glucose in the medium and hydrolysed both apple and tomato cutins. Inducers included apple cutin, apple pomace, tomato peel, potato suberin and commercial cork. Unlike similar fungal enzymes, the T. vulgaris cutinolytic esterase was not inducible by cutin hydrolysate. The cutinolytic esterase exhibited a half-life of over 60 min at 70 degrees C and a pH optimum of >/= 11.0. This study indicates that thermophylic filamentous bacteria may be excellent commercial sources of heat-stable cutin-degrading enzymes that can be produced by fermentation of low cost feedstocks. PMID:10886609

  5. 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

  6. Stochastic Optimization for Machine Learning

    E-print Network

    Powell, Warren B.

    Stochastic Optimization for Machine Learning ICML 2010, Haifa, Israel Tutorial by Nati Srebro Descent: formulation, analysis and use in machine learning · Learn about extensions and generalizations, and their Machine Learning counterparts Main Goal: Machine Learning is Stochastic Optimization #12;Outline

  7. Observations of Upwelling Filaments in the Southern North-West African Upwelling System : a Joint Effect of the Bottom Topography and the Offshore Eddy Field?

    NASA Astrophysics Data System (ADS)

    Meunier, T.; Barton, E. D.; Torres, R.; Barreiro, B.

    2010-12-01

    The nature and dynamics of the long filaments forming in the southern edge of the West-African upwelling system are investigated using data from the SOLAS-ICON cruise, that took place in April-May 2009 offshore of Cap Blanc, between 19.5 and 22.5 °N and 17 and 19 °W. Two synoptic hydrographic surveys using a Moving Vessel Profiler were performed at a 15 days interval on two distinct upwelling filaments at different stages of development. The first survey showed the presence of a large anticyconic eddy North of the filament, also evident in the satellite imagery. Two transects were performed across the tip of the filament, showing a steep rising of the isohalines and the isotherms, with horizontal gradients of 3.10-2 psu km-1 and 10 -1 °C km-1. The density compensation of temperature and salinity in this part of the North West African upwelling system resulted in a weaker doming of the isopycnals across the filament. The second filament developed during a strong wind episode directly following a 2 days wind relaxation period. 8 cross sections were performed, all showing a steeper doming of the isohalines and isotherms than during the first survey, resulting in horizontal gradients of 8.10-2 psu km-1 and 5.10-1 °C km-1 near the surface. The hydrographic signature of the filament was evident as deep as 300 m. Satellite imagery showed the persistence between the two surveys of a shorter and colder filament West of Cap Blanc , rolling around a small anticyclonic eddy, in spite of the relaxation of the wind. The surveyed filaments both appeared to emerge from this struc ture. A process study using a simple two layer shallow water isopycnic numerical model (MICOM) and an idealized topography was carried out to elucidate the development and stationarity of the anticyclone and cold filament at the root of the longer structures. Potential vorticity anomalies generated by topographic effects were shown to play a major role in the filament formation, when interacting with the upwelling front. The presence of the Cabo Verde frontal zone in the vicinity of the upwelling system is assumed to be responsible for the different behavior in the evolution of the 2 surveyed filaments : previous studies (Spall, 1992; Onken and Klein, 1991; Joyce et al., 1998) showed that the Cabo Verde front was baroclinically unstable and thus an important source of eddy activity in the region. The variability in the evolution of the offshore extension of the observed filaments are believed to be related with this external mesoscale activity. As the topographic eddies can trigger permanent meanders on the upwelling front, the resulting structures can be stretched and evolve into more complex and variable patterns by the interaction with the external eddy field.

  8. Wind Tunnel 

    E-print Network

    Unknown

    2011-08-17

    . . . . . . . . . . . . . . . . . . , . 67 APPENDIX G DISTRIBUTION OE LAKE CHARLES OBSERVED WIND DIPUECT1ON Wl', 'N TUE OUSL'RVL'D UOUSTON WIND DIR). CTION IS 1'ROill 'lklE EAST-NORTH- EAST, EAST, OR EAST- SOU'lklEAS'lL. . . . . . . . . . P aBa 72 APPENDIX II DETAII ED SOLUT10N... levels ro the results obtained b; rcg: i ssinf the Uouston low- levcl !&inde-aloft on the Houston surface wind. Althou?h d Leisure correlation coofficip!its show a definite urmr)er siinisiurs, they indicate that from &iB'/. to 77X (depending on season...

  9. Stellar Winds

    NASA Astrophysics Data System (ADS)

    Owocki, Stan

    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.

  10. Covering selfish machines

    Microsoft Academic Search

    Leah Epstein; Rob Van Stee

    2006-01-01

    We consider the machine covering problem for selfish related machines. For a constant number of machines, m, we show a monotone polynomial time approximation scheme (PTAS) with running time that is linear in the number of jobs. It uses a new technique for reducing the number of jobs while remaining close to the optimal solution. We also present an FPTAS

  11. Automated Slide Staining Machine

    PubMed Central

    Drew, W. Lawrence; Pedersen, Anders N.; Roy, Jacques J.

    1972-01-01

    A machine is described which can perform the Gram stain. Comparison of slides stained by machine versus hand revealed no difference in reproducibility or accuracy. In addition to providing clean, dry, uniformly stained slides, the machine saves 24 sec per slide when compared with a hand staining technique. Images PMID:4110426

  12. Review on ultrasonic machining

    Microsoft Academic Search

    T. B. Thoe; D. K. Aspinwall; M. L. H. Wise

    1998-01-01

    Ultrasonic machining is of particular interest for the cutting of non-conductive, brittle workpiece materials such as engineering ceramics. Unlike other non-traditional processes such as laser beam, and electrical discharge machining, etc., ultrasonic machining does not thermally damage the workpiece or appear to introduce significant levels of residual stress, which is important for the survival of brittle materials in service. The

  13. Find the Simple Machines

    NSDL National Science Digital Library

    2012-07-17

    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.

  14. Analyzing the temporal variation of wind turbine responses using Gaussian Mixture Model and Gaussian Discriminant Analysis

    E-print Network

    Stanford University

    1 Analyzing the temporal variation of wind turbine responses using Gaussian Mixture Model characteristics have a significant impact on the structural response and the lifespan of wind turbines. This paper presents a machine learning approach towards analyzing and predicting the response of a wind turbine

  15. A Comprehensive Overview on Reactive Power Compensation Technologies for Wind Power Applications

    Microsoft Academic Search

    Ahmed Faheem Zobaa; Milutin Jovanovic

    2006-01-01

    The size and number of wind farms contributing to the energy production is continuously growing. The rating of wind turbines has increased from less than 1 MW a few years ago to 2- to 3-MW being installed today with 5-MW machines under development. The interaction of the wind farm, reactive power compensators, and the associated power network is being investigated.

  16. A corrected hybrid approach for wind speed prediction in Hexi Corridor of China

    Microsoft Academic Search

    Zhenhai Guo; Jing Zhao; Wenyu Zhang; Jianzhou Wang

    2011-01-01

    Wind energy has been well recognized as a renewable resource in electricity generation, which is environmentally friendly, socially beneficial and economically competitive. For proper and efficient evaluation of wind energy, a hybrid Seasonal Auto-Regression Integrated Moving Average and Least Square Support Vector Machine (SARIMA–LSSVM) model is significantly developed to predict the mean monthly wind speed in Hexi Corridor. The design

  17. Circulating current analysis in the parallel-connected windings of synchronous generators under abnormal operating conditions

    Microsoft Academic Search

    A. Foggia; J.-E. Torlay; C. Corenwinder; A. Audoli; J. Herigault

    1999-01-01

    In large synchronous generators, the windings are usually parallel-connected in order to deliver the normal characteristics at the terminals of the machines. Under normal conditions, there is no circulating current between the windings of one phase. But when a failure occurs like an eccentricity or some other faults, the symmetry between parallel windings is broken and a circulating current will

  18. The 100 kW experimental wind turbine generator project

    NASA Technical Reports Server (NTRS)

    Puthoff, R. L.; Sirocky, P.

    1975-01-01

    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.

  19. Phytoplankton pigment patterns and wind forcing off central California

    NASA Technical Reports Server (NTRS)

    Abbott, Mark R.; Barksdale, Brett

    1991-01-01

    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.

  20. Filamentous nature of pheromone plumes protects integrity of signal from background chemical noise in cabbage looper moth,Trichoplusia ni.

    PubMed

    Liu, Y B; Haynes, K F

    1992-03-01

    (Z)-7-Dodecenol failed to interrupt pheromone-mediated anemotactic responses by male cabbage looper moths,Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) in a wind tunnel when released 5 cm crosswind on both sides of the pheromone source or 10 cm upwind of the source to create an overlapping plume downwind. Significant inhibitory effects of (Z)-7-dodecenol were observed when released with the six-component pheromone blend from the same septum or abutting septa. These results indicate that (Z)-7-dodecenol needs to be received simultaneously with the pheromone blend to inhibit the anemotactic responses of males to the sex pheromone. We suggest that this feature and the filamentous nature of pheromone plumes render pheromone signals relatively protected from background chemical noise that may originate from pheromone plumes of other insect species. Unless filaments from a pheromone signal and an inhibitor arrive simultaneously, the integrity of the signal is maintained. PMID:24254938

  1. Acoustic Emission from Single and Multiple Kevlar 49 Filament Breaks

    Microsoft Academic Search

    Marvin A. Hamstad; Richard L. Moore

    1986-01-01

    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

  2. Local stability of a gravitating filament: a dispersion relation

    NASA Astrophysics Data System (ADS)

    Freundlich, J.; Jog, C. J.; Combes, F.

    2014-04-01

    Filamentary structures are ubiquitous in astrophysics and are observed at various scales. On a cosmological scale, matter is usually distributed along filaments, and filaments are also typical features of the interstellar medium. Within a cosmic filament, matter can contract and form galaxies, whereas an interstellar gas filament can clump into a series of bead-like structures that can then turn into stars. To investigate the growth of such instabilities, we derive a local dispersion relation for an idealized self-gravitating filament and study some of its properties. Our idealized picture consists of an infinite self-gravitating and rotating cylinder with pressure and density related by a polytropic equation of state. We assume no specific density distribution, treat matter as a fluid, and use hydrodynamics to derive the linearized equations that govern the local perturbations. We obtain a dispersion relation for axisymmetric perturbations and study its properties in the (kR, kz) phase space, where kR and kz are the radial and longitudinal wavenumbers, respectively. While the boundary between the stable and unstable regimes is symmetrical in kR and kz and analogous to the Jeans criterion, the most unstable mode displays an asymmetry that could constrain the shape of the structures that form within the filament. Here the results are applied to a fiducial interstellar filament, but could be extended for other astrophysical systems, such as cosmological filaments and tidal tails. Appendices are available in electronic form at http://www.aanda.org

  3. Self-organized bundle of lasing filaments in dense media

    Microsoft Academic Search

    L. Guyon; F. Courvoisier; V. Boutou; R. Nuter; A. Vincotte; S. Champeaux; L. Berge; P. Glorieux; J.-P. Wolf

    2006-01-01

    The filamentation of powerful, ultrashort laser pulses in liquids is investigated. It is shown that the multiple filaments produced in ethanol can be modified into controllable, regular patterns by doping the medium with dyes at high concentrations. Experimental results are confirmed by three-dimensional numerical simulations. Pump-dump pulse experiments furthermore reveal that the stimulated emission from excited dye molecules in the

  4. The art and design of genetic screens: filamentous fungi

    Microsoft Academic Search

    Miriam Zolan; Lorna Casselton

    2002-01-01

    In the 1940s, screens for metabolic mutants of the filamentous fungus Neurospora crassa established the fundamental, one-to-one relationship between a gene and a specific protein, and also established fungi as important genetic organisms. Today, a wide range of filamentous species, which represents a billion years of evolutionary divergence, is used for experimental studies. The developmental complexity of these fungi sets

  5. PROGRESS IN EXPERIMENTAL STUDY OF CURRENT FILAMENTATION INSTABILITY*

    E-print Network

    Brookhaven National Laboratory

    resulting in the generation of large magnetic fields and radiation. The generation of magnetic fieldsPROGRESS IN EXPERIMENTAL STUDY OF CURRENT FILAMENTATION INSTABILITY* Brian Allen# , Patric Muggli, University of California at Los Angeles Los Angeles, CA 90095 USA Abstract Current Filamentation Instability

  6. BIOCHEMICAL AND IMMUNOLOGICAL ANALYSIS OF RAPIDLY PURIFIED 10-nm FILAMENTS

    E-print Network

    Goldman, Robert D.

    .4. The solubilized components assemble into distinct 10-nm filaments upon the addition of 0.171 M sodium chloride-buffered saline. Purified FC are birefringent and retain the pattern of distribution of 10-rim filaments,000 molecular weight on sodium dodecyl sulfate (SDS) polyacrylamide gels. The protein is immunologically

  7. Verifying Stiffness Parameters Of Filament-Wound Cylinders

    NASA Technical Reports Server (NTRS)

    Verderaime, V.; Rheinfurth, M.

    1994-01-01

    Predicted engineering stiffness parameters of filament-wound composite-material cylinders verified with respect to experimental data, by use of equations developed straightforwardly from applicable formulation of Hooke's law. Equations derived in engineering study of filament-wound rocket-motor cases, also applicable to other cylindrical pressure vessels made of orthotropic materials.

  8. Method for simultaneously coating a plurality of filaments

    DOEpatents

    Miller, P.A.; Pochan, P.D.; Siegal, M.P.; Dominguez, F.

    1995-07-11

    Methods and apparatuses are disclosed 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. 3 figs.

  9. Filament-wound spar shell graphite/epoxy fan blades

    NASA Technical Reports Server (NTRS)

    Yao, S.

    1976-01-01

    The methodology for fabrication of wet filament wound spar shell fan blades is presented. All principal structural elements were filament wound, assembled, formed, bonded and co-cured in a female mold. A pair of blades were fabricated as one integral unit and parted into two after curing.

  10. Galaxy Spin Alignment in Filaments and Sheets: Observational Evidence

    NASA Astrophysics Data System (ADS)

    Tempel, Elmo; Libeskind, Noam I.

    2013-10-01

    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.

  11. Probing the cosmic web: intercluster filament detection using gravitational lensing

    Microsoft Academic Search

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

    2010-01-01

    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

  12. GALAXY SPIN ALIGNMENT IN FILAMENTS AND SHEETS: OBSERVATIONAL EVIDENCE

    SciTech Connect

    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

    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.

  13. Motion of a Vortex Filament in the Half Space

    E-print Network

    Aiki, Masashi

    2010-01-01

    A model equation for the motion of a vortex filament immersed in three dimensional, incompressible and inviscid fluid is investigated as a humble attempt to model the motion of a tornado. We solve an initial-boundary value problem in the half space where we impose a boundary condition in which the vortex filament is allowed to move on the boundary.

  14. CYTOPLASMIC FILAMENTS IN DEVELOPING AND ADULT VERTEBRATE SMOOTH MUSCLE

    Microsoft Academic Search

    Y. Uehara; G. R. CAMPBELL; G. BURNSTOCK

    1971-01-01

    An extensive study of adult and developing smooth muscle has revealed the widespread occurrence of a distinct filament with an average diameter of about 100 A (termed the 100 A filament) . Unlike that of myofilaments, their appearance in longitudinal section is uniform, but in transverse section they have a round profile, occasionally exhibiting a less electron-opaque core . The

  15. Statistical analysis of magnetic field inversion in filaments with the Solar Feature Catalogues

    Microsoft Academic Search

    V. V. Zharkova; S. S. Ipson; J. Aboudarham; N. Fuller; A. K. Benkhalil; S. I. Zharkov

    2004-01-01

    This paper utilizes the Solar Feature Catalogues with detected filaments on the in Halpha images at the Meudon Observatory in France and filament channels observed in EIT using the fast robust procedure for automatic detection of filaments and filament skeletons. The detected filaments and filament channel are examined for their co-alignment with the line-of-sight (LOS) magnetic inversion line maps obtained

  16. Thin phytoplankton layer formation at eddies, filaments, and fronts in a coastal upwelling zone

    NASA Astrophysics Data System (ADS)

    Johnston, T. M. Shaun; Cheriton, Olivia M.; Pennington, J. Timothy; Chavez, Francisco P.

    2009-02-01

    On two cruises in August and September 2003 (hereafter cruises 2 and 3) during wind relaxations and transitions to upwelling conditions, thin layers of phytoplankton were observed in or a few meters below the stratified transition layer at the mixed layer base and in regions of sheared flow on the flanks of eddies, filaments, and fronts near Monterey Bay, California. On an earlier cruise in August (cruise 1), no thin layers were found after a prolonged wind relaxation. Chlorophyll concentrations and shear were both an order of magnitude less than on cruises 2 and 3. Our vertical profiles were made using a fluorometer mounted on a conductivity-temperature-depth package, which was lowered from the ship as slowly as 0.25ms-1 every 10 km on five ˜80-km cross-shore transects. Remotely sensed sea-surface temperature, chlorophyll, and currents are required to understand the temporal and spatial evolution of the circulation and to interpret the quasi-synoptic in situ data. Decorrelation scales are ˜20km from lagged temperature and salinity covariances. Objectively mapped sections of the in situ data indicate the waters containing thin layers were recently upwelled at either the Point Sur or Point Año Nuevo upwelling centers. Spatially limited distributions of phytoplankton at the coastal upwelling centers ( ˜40km alongshore, 20 km cross-shore, and 30 m thick) were transformed into thin layers by current shear and isolated from wind-driven vertical mixing by the stratification maximum of the transition layer. Vertically sheared horizontal currents on the flanks of the eddies, filaments, and fronts horizontally stretched and vertically thinned phytoplankton distributions. These thin, elongated structures were then observed as thin layers of phytoplankton in vertical fluorescence profiles at four stations on cruise 2 and eight stations on cruise 3. Light winds during relaxations did not mix away these thin layers. On cruise 2, thin layers were found at eddies at the inshore and offshore ends of a 100-km-long filament, while broader subsurface chlorophyll maxima were found along the filament. This result suggests that higher-resolution sampling along and across a filament may find thin layers forming and dissipating along its length. On cruise 3, thin layers were found at three adjacent stations across an upwelling front and may have extended continuously for >20km, but neither species composition nor bio-optical data are available to confirm this conjecture. The thin layers were 1-5 m thick in the vertical at full width half maximum and had peak fluorescence values from 7-30mgm-3. (Bottle chlorophyll samples showed fluorometer chlorophyll readings may have been 1.3-1.5×too large, but the scatter in this relation was considerable especially at the larger fluorescence values detected in thin layers.) While sheared currents thinned an initially thick subsurface chlorophyll maximum into thin layers, the peak values in these thin layers exceeded concentrations in the upwelled source waters and were unexplained by our data.

  17. Reduction of force exciting influences to decrease radiation of acoustic noise in synchronous machines

    Microsoft Academic Search

    Stephan Schulte; Kay Hameyer

    2007-01-01

    Purpose – The paper aims to provide an approach to actively decrease the radiation of acoustic noise in synchronous machines. Design\\/methodology\\/approach – Splitting regular three-phase windings of synchronous machines into two independent three-phase systems allows for an active influence of the current waveform if both winding systems are mutually displaced against each other. The harmonics content of each phase-current varies

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

    NASA Technical Reports Server (NTRS)

    1975-01-01

    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.

  19. Impact of motor molecules on the dynamics of treadmilling filaments

    NASA Astrophysics Data System (ADS)

    Erlenkämper, Christoph; Johann, Denis; Kruse, Karsten

    2012-11-01

    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.

  20. Successive filament eruptions within one solar breakout event

    NASA Astrophysics Data System (ADS)

    Shen, Yuandeng

    2014-01-01

    The magnetic breakout model has been widely used to explain solar eruptive activities. Here, we apply it to explain successive filament eruptions occurred in a quadrupolar magnetic source region. Based on the high temporal and spatial resolution, multi-wavelengths observations taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO), we find some signatures that support the occurrence of breakout-like external reconnection just before the start of the successive filament eruptions. Furthermore, the extrapolated three-dimensional coronal field also reveals that the magnetic topology above the quadrupolar source region resembles that of the breakout model. We propose a possible mechanism within the framework of the breakout model to interpret the successive filament eruptions, in which the so-called magnetic implosion mechanism is firstly introduced to be the physical linkage of successive filament eruptions. We conclude that the structural properties of coronal fields are important for producing successive filament eruptions.

  1. Colloquium: Geometry and optimal packing of twisted columns and filaments

    NASA Astrophysics Data System (ADS)

    Grason, Gregory M.

    2015-04-01

    This Colloquium presents recent progress in understanding constraints and consequences of close-packing geometry of filamentous or columnar materials possessing nontrivial textures, focusing, in particular, on the common motifs of twisted and toroidal structures. The mathematical framework is presented that relates spacing between linelike, filamentous elements to their backbone orientations, highlighting the explicit connection between the interfilament metric properties and the geometry of non-Euclidean surfaces. The consequences of the hidden connection between packing in twisted filament bundles and packing on positively curved surfaces, like the Thomson problem, are demonstrated for the defect-riddled ground states of physical models of twisted filament bundles. The connection between the "ideal" geometry of fibrations of curved three-dimensional space, including the Hopf fibration, and the non-Euclidean constraints of filament packing in twisted and toroidal bundles is presented, with a focus on the broader dependence of metric geometry on the simultaneous twisting and folding of multifilament bundles.

  2. Ultrasonic analysis of Kevlar-epoxy filament wound structures

    SciTech Connect

    Brosey, W.D.

    1985-07-16

    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.

  3. Cluster-formation in the Rosette molecular cloud at the junctions of filaments

    NASA Astrophysics Data System (ADS)

    Schneider, N.; Csengeri, T.; Hennemann, M.; Motte, F.; Didelon, P.; Federrath, C.; Bontemps, S.; Di Francesco, J.; Arzoumanian, D.; Minier, V.; André, Ph.; Hill, T.; Zavagno, A.; Nguyen-Luong, Q.; Attard, M.; Bernard, J.-Ph.; Elia, D.; Fallscheer, C.; Griffin, M.; Kirk, J.; Klessen, R.; Könyves, V.; Martin, P.; Men'shchikov, A.; Palmeirim, P.; Peretto, N.; Pestalozzi, M.; Russeil, D.; Sadavoy, S.; Sousbie, T.; Testi, L.; Tremblin, P.; Ward-Thompson, D.; White, G.

    2012-04-01

    Aims: For many years feedback processes generated by OB-stars in molecular clouds, including expanding ionization fronts, stellar winds, or UV-radiation, have been proposed to trigger subsequent star formation. However, hydrodynamic models including radiation and gravity show that UV-illumination has little or no impact on the global dynamical evolution of the cloud. Instead, gravitational collapse of filaments and/or merging of filamentary structures can lead to building up dense high-mass star-forming clumps. However, the overall density structure of the cloud has a large influence on this process, and requires a better understanding. Methods: The Rosette molecular cloud, irradiated by the NGC 2244 cluster, is a template region for triggered star-formation, and we investigated its spatial and density structure by applying a curvelet analysis, a filament-tracing algorithm (DisPerSE), and probability density functions (PDFs) on Herschel column density maps, obtained within the HOBYS key program. Results: The analysis reveals not only the filamentary structure of the cloud but also that all known infrared clusters except one lie at junctions of filaments, as predicted by turbulence simulations. The PDFs of sub-regions in the cloud show systematic differences. The two UV-exposed regions have a double-peaked PDF we interprete as caused by shock compression, while the PDFs of the center and other cloud parts are more complex, partly with a power-law tail. A deviation of the log-normal PDF form occurs at AV ? 9m for the center, and around 4m for the other regions. Only the part of the cloud farthest from the Rosette nebula shows a log-normal PDF. Conclusions: The deviations of the PDF from the log-normal shape typically associated with low- and high-mass star-forming regions at AV ? 3-4m and 8-10m, respectively, are found here within the very same cloud. This shows that there is no fundamental difference in the density structure of low- and high-mass star-forming regions. We conclude that star-formation in Rosette - and probably in high-mass star-forming clouds in general - is not globally triggered by the impact of UV-radiation. Moreover, star formation takes place in filaments that arose from the primordial turbulent structure built up during the formation of the cloud. Clusters form at filament mergers, but star formation can be locally induced in the direct interaction zone between an expanding H II-region and the molecular cloud. Figures 4-6 and Appendices A-C are available in electronic form at http://www.aanda.org

  4. Etude et simulation des groupes convertisseurs-machines synchrones a six phases

    NASA Astrophysics Data System (ADS)

    Doyon, Jean-Francois

    Since many years, multiphase (n > 3) machines represent a growing research interest in the electrical machines domain. This type of machine can be used for many systems like automotive electrical traction, electric ship propulsion, wind farms or high-power industrial applications. Above all multiphase machines, the six phases wounded rotor synchronous machine brings a huge interest. Subsequently, using that kind of machine in any application requires a good understanding of the machine model and its respective converters. Hence, simulation represents a great way to study the behaviour and design of such applications that uses six phases wounded rotor synchronous machines. The present research concerns the study and simulation of six phase synchronous machinesconverters systems. From this project resulted the implementation of the six phases wound rotor salient pole synchronous machine in the Demos library of Matlab SimPowerSytems. In terms of study, a six phase machine electric drive is designed as well as a six phase machine implementation in a type 4 wind farm. The modeling of the six phase synchronous machine is fully detailed for the electrical part and the mechanical part. Then, the voltage source inverter electric drive with hysteresis control is conceived. Simulations of torque control, speed control and degraded mode of the machine are executed. The results illustrate the electric drive efficiency. This is followed by the type 4 wind turbine application of the machine. The wind farm is connected to a 120 kV grid, where a voltage drop fault appears at the 120 kV bar for a duration of six 60 Hz cycles. The results show a good operation of the regulators during the fault. This application is also subjected to a degraded mode, where results illustrate once again a good system regulation. Also, for the electric drive and the wind farm applications, a comparative study is made for the use of an asymmetrical versus symmetrical winding configuration of the machine. It is shown that for these two configurations, the total harmonic distortion seen from the source are similar. Finally, detailed model and average model of the converters are made for the electric drive and the wind turbine. The results show great similarity between the models.

  5. The plasma filamentation instability in one dimension: nonlinear evolution

    NASA Astrophysics Data System (ADS)

    Rowlands, G.; Dieckmann, M. E.; Shukla, P. K.

    2007-08-01

    The plasma filamentation instability or beam-Weibel instability generates magnetic fields and accelerates particles in collisionless astrophysical plasma. This instability has been examined with multi-dimensional particle-in-cell (PIC) simulations, demonstrating the formation of current flux tubes. Such simulations could not model a statistically significant number of filaments. Here, we model with a PIC simulation the filamentation instability that is driven by nonrelativistic, cool electron beams in one spatial dimension at an unprecedented resolution. We show unambiguously that the gradient of the magnetic pressure which develops during the quasi-linear evolution of the filamentation instability, gives rise to an electrostatic field component. The interplay of the magnetic and electrostatic fields results in a wavenumber spectrum of the magnetic field that is a power-law, which has been reported previously for multi-dimensional PIC simulations. The magnetic field power spectrum decreases with the exponent -5.7 and that of the electrostatic field with -3.8, yielding a ratio of 3:2. The electromagnetic fields thermalize the electrons. The electrons develop a velocity distribution in the simulation direction that decreases exponentially at low speeds and faster at high speeds. The filamentation instability can thus not efficiently accelerate electrons to high energies. The filaments develop into a stationary final state. The probability distribution of the filament sizes is a Gumbel distribution. In astrophysical settings, this implies that the long exponential tail of this distribution may lead with a reasonable probability to large current filaments, if the filamentation instability develops in a large enough volume. The coherent magnetic fields of large filaments are required to explain the synchrotron emissions of gamma ray bursts.

  6. Composite rotor blades for wind turbine generators

    NASA Astrophysics Data System (ADS)

    Weigel, W. D.

    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.

  7. Collisionless filamentation, filament merger and heating of low-density relativistic electron beam propagating through a background plasma

    Microsoft Academic Search

    Vladimir Khudik; Igor Kaganovich; Gennady Shvets

    2011-01-01

    A cold electron beam propagating through a background plasma is subject to filamentation process due to theWeibel instability. If the initial beam radius is large compared with the electron skin depth and the beam density is much smaller than the background plasma density, multiple filaments merge many times. Because of this non-adiabatic process, the beam perpendicular energy of initially cold

  8. The Mod-2 wind turbine development project

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  9. The NASA Lewis large wind turbine program

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  10. Brightenings Associated with Falling Filament Material

    NASA Astrophysics Data System (ADS)

    Gilbert, H. R.; Inglis, A. R.; Mays, M. L.; Ofman, L.; Provornikova, E.; Thompson, B. J.; Young, C. A.

    2014-12-01

    Solar filaments exhibit a range of eruptive-like dynamic activity, including in some cases the confined or 'failed' ejection of prominence material from the solar atmosphere. In rare cases material that fails to erupt exhibits a strong interaction with the lower corona as the material returns to the solar surface, observed as substantial broadband brightening of EUV emission. We investigate a selection of recent partial prominence eruptions in order to understand the apparent rarity of the brightening phenomenon. Using combined data from SDO/AIA and STEREO, we explore the energetics and kinematics of these events, assessing the likely conditions of both the corona and the prominence material that are required in order to explain these EUV brightenings. We further demonstrate the potential of this phenomenon as diagnostic tool for both prominence material conditions and the coronal magnetic field.

  11. Introducing intermediate filaments: from discovery to disease

    PubMed Central

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

    2009-01-01

    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

  12. Cryogenic glass-filament-wound tank evaluation

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

    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.

  13. Similarity of the Yeast RAD51 Filament to the Bacterial RecA Filament

    Microsoft Academic Search

    Tomoko Ogawa; Xiong Yu; Akira Shinohara; Edward H. Egelman

    1993-01-01

    The RAD51 protein functions in the processes of DNA repair and in mitotic and meiotic genetic recombination in the yeast Saccharomyces cerevisiae. The protein has adenosine triphosphate-dependent DNA binding activities similar to those of the Escherichia coli RecA protein, and the two proteins have 30 percent sequence homology. RAD51 polymerized on double-stranded DNA to form a helical filament nearly identical

  14. Some Properties of Femtosecond Laser Filamentation Relevant to Atmospheric Applications Part I. The Robustness of Filamentation

    Microsoft Academic Search

    Jerome Kasparian; UMR CNRS

    2007-01-01

    When ultrashort (fs), high-power laser pulses propagate through the atmosphere, extended plasma filaments form and emit white\\u000a light in a spectral range spanning from the ultraviolet (230 nm) to the infrared (4.5 µm). This strongly non-linear optical\\u000a phenomenon results from a dynamical balance between respectively focusing and defocusing Kerr- and plasma-lenses, which are\\u000a formed by a nonuniform, intensity-dependent refractive index

  15. Influence of soft magnetic materials on the design and performance of tubular permanent magnet machines

    Microsoft Academic Search

    Jiabin Wang; David Howe

    2005-01-01

    This paper investigates the influence of the choice of soft magnetic material on the performance of a tubular permanent magnet machine, and quantifies the relative merits of silicon iron laminations and soft magnetic composites (SMCs). The machine is equipped with a modular stator winding and employs a quasi-Halbach magnetized moving-magnet armature. It is shown that, despite its poorer space utilization,

  16. Implementation of the Three-Phase Switched Reluctance Machine System for Motors and Generators

    Microsoft Academic Search

    Hao Chen; Jason J. Gu

    2010-01-01

    This paper presents two three-phase switched reluctance machine systems. One is the dual motors drive for the electric locomotive traction; the other is the variable-speed generator system for wind power applications. The principles of the switched reluctance machine system operated at four quadrants, the scheme of the symmetrical traction at quadrant I and quadrant III, and the scheme of the

  17. Effect of Paralleling the Stator Coils in a Permanent-Magnet Machine

    Microsoft Academic Search

    Mohammad S. Islam; Sayeed Mir; Tomy Sebastian

    2006-01-01

    As low-voltage machines require smaller number of turns per phase compared to higher voltage machines, it is normal to connect the various stator phase coils in parallel to form the phase winding. The placement of various coil sides in the slot and the difference in the field produced by different poles of the rotor magnet can influence the induced voltage

  18. Analysis and design of contactless self-resonant induced movable chopper for the linear synchronous machine

    Microsoft Academic Search

    Jian-Long Kuo; Zen-Shan Chang; Jiann-Der Lee; Ping-Hsun Lee

    2002-01-01

    This paper presents an expandable and flexible contactless induced movable chopper for linear synchronous machines. By using a ringing choke converter with distributed parallel windings (DPW-RCC), the configuration will be easily expanded when the power rating is increased for the linear synchronous machine. Therefore no further re-design work is required. The associated analysis and design for the chopper by using

  19. Abstract --This paper presents a theoretical approach as far as faulty Permanent Magnet Synchronous Machines

    E-print Network

    Paris-Sud XI, Université de

    Synchronous Machines (PMSM) are concerned. The knowledge of PMSM's behavior under inter-turn fault is very method based on FEA and winding Modeling of PM Synchronous Machines Under Inter-turn Fault N. Leboeuf, T fault conditions without using circuit models coupled with finite element analysis (FEA). The method

  20. Contactless self-resonant induced movable converter for the linear synchronous machine

    Microsoft Academic Search

    Jian-Long Kuo; Zen-Shan Chang; Jiann-Der Lee; Ping-Hsun Lee

    2002-01-01

    This paper provides expandable and flexible contactless induced movable chopper for the linear synchronous machine. By using the ringing choke converter with distributed parallel windings (DPW-RCC), the configuration will be easily expanded when the power rating is increased for the linear synchronous machine. Therefore, no further redesign work is required. The associated analysis and design for the chopper by using

  1. An equivalent circuit for the Brushless Doubly Fed Machine (BDFM) including parameter estimation

    E-print Network

    Cambridge, University of

    described. Expressions for the torque as a function of speed have been derived and predictions of machine. The work illustrates the link between rotor equivalent circuit parameters and machine performance the same principle and showed that suitably designed stator and rotor windings could reduce copper losses

  2. Analysis of Electromechanical Interactions in a Flywheel System With a Doubly Fed Induction Machine

    Microsoft Academic Search

    Li Ran; Dawei Xiang; James L. Kirtley

    2011-01-01

    This paper analyzes the electromechanical interac- tion 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 is subject to power control, and this can cause it to produce negative damping to the shaft torsional vibration. Resonance must be prevented, and this paper proposes a

  3. Post-Assembly Magnetization of Rare-Earth Fractional-Slot Surface Permanent-Magnet Machines Using a Two-Shot Method

    Microsoft Academic Search

    Min-Fu Hsieh; Yao-Min Lien; David G. Dorrell

    2011-01-01

    This paper studies the post-assembly magnetization of a fractional-slot, concentrated winding brushless rare-earth surface permanent-magnet machine with six rotor poles and nine stator slots. In the paper, the simulation method is discussed, and it is illustrated that it is possible to fully magnetize the machine after assembly using two pulses of the winding (\\

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

    NASA Technical Reports Server (NTRS)

    Debolt, H. E.; Krukonis, V. J.

    1973-01-01

    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.

  5. Rapid longitudinal migrations of the filament front off Namibia (SE Atlantic) during the past 70 kyr

    NASA Astrophysics Data System (ADS)

    Romero, O. E.; Crosta, X.; Kim, J.-H.; Pichevin, L.; Crespin, J.

    2015-02-01

    Although productivity variations in coastal upwelling areas are mostly attributed to changes in wind strength, productivity dynamics in the Benguela Upwelling System (BUS) is less straightforward due to its complex atmospheric and hydrographic settings. In view of these settings, past productivity variations in the BUS can be better investigated with downcore sediments representing different productivity regimes. In this study, two sediment cores retrieved at ca. 25°-26°S in the BUS and representing different productivity regimes were studied. By using micropaleontological, geochemical and temperature proxies measured on core MD96-2098, recovered at 2910 m water depth in the bathypelagic zone at 26°S off Namibia, variations of filament front location, productivity and temperature in the central BUS over the past 70 kyr were reconstructed. The comparison with newly-generated alkenone-based sea-surface temperature (SST) and previously obtained data at site GeoB3606-1 (~ 25°S; ca. 50 km shoreward from MD96-2098) allowed the recognition of four main phases: (1) upwelling front above the mid slope (70 kyr-44 kyr), (2) seaward displacement of the upwelling front beyond the mid slope (44 kyr-31 kyr), (3) main upwelling front over the hemipelagial (31 kyr-19 kyr), and (4) shoreward contraction of the upwelling filament, and decreased upwelling strength over most of the uppermost bathypelagic (19 kyr-6 kyr). The latitudinal migration of the Southern Hemisphere westerlies and the consequent contractions and expansions of the subpolar gyre played a significant role in millennial and submillennial variability of SST off Namibia. The strength of the southeasterly trade winds, rapid sea-level variations and the equatorward leakage of Antarctic silicate might have acted as amplifiers. Although late Quaternary variations of productivity and upwelling intensity in eastern boundary current systems are thought to be primarily linked to the variability in wind stress, this multi-parameter reconstruction shows that interplaying mechanisms defined the temporal variation pattern of the filament front migrations and the diatom production off Namibia during the past 70 kyr.

  6. Present status and future trends of R&D for HTS rotational machines in Japan

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Osami

    2014-09-01

    Various HTS rotating machines, from multiple MW class to several 10 kW class, are being developed in Japan. R&D statuses of those machines are reviewed. Design studies of various types of HTS wind power generators are also conducted in Japan and their merits and demerits are discussed. Based on the present R&D statuses, future technical trends of HTS machines are discussed.

  7. An analysis on the characteristics of a synchronous machine connected to a d.c.-link

    Microsoft Academic Search

    S. Moriyasu; C. Uenosono

    1986-01-01

    Contents The synchronous machine connected to a d.c.-link is used for either a generator or a motor by connecting a bridge rectifier to the terminals of armature windings. —Since the synchronous machine repeats line-to-line short circuiting six times in one cycle due to commutation, it is different from ordinary synchronous machine in respect of operational characteristics and design consideration. —

  8. Towards Real-Time Detection and Tracking of Blob-Filaments in Fusion Plasma Big Data

    E-print Network

    Wu, Lingfei; Sim, Alex; Churchill, Michael; Choi, Jong Y; Stathopoulos, Andreas; Chang, Cs; Klasky, Scott

    2015-01-01

    Magnetic fusion could provide an inexhaustible, clean, and safe solution to the global energy needs. The success of magnetically-confined fusion reactors demands steady-state plasma confinement which is challenged by the blob-filaments driven by the edge turbulence. Real-time analysis can be used to monitor the progress of fusion experiments and prevent catastrophic events. However, terabytes of data are generated over short time periods in fusion experiments. Timely access to and analyzing this amount of data demands properly responding to extreme scale computing and big data challenges. In this paper, we apply outlier detection techniques to effectively tackle the fusion blob detection problem on extremely large parallel machines. We present a real-time region outlier detection algorithm to efficiently find blobs in fusion experiments and simulations. In addition, we propose an efficient scheme to track the movement of region outliers over time. We have implemented our algorithms with hybrid MPI/OpenMP and ...

  9. Effects of external environments on the short beam shear strength of filament wound graphite/epoxy

    NASA Technical Reports Server (NTRS)

    Penn, B. G.; Clemons, J. M.

    1986-01-01

    Filament wound graphite/epoxy samples were immersed in seawater, deionized water, and toluene at room temperature and 80 deg C for 5, 15, and 43 days, and in methanol at room temperature for 15 and 43 days. The percent weight gains and short beam shear strengths were determined after environmental exposure. Samples immersed in deionized water and seawater had higher percent weight gains than those immersed in toluene at room temperature and 80 deg C. The percent weight gains for samples immersed in methanol at room temperature were comparable to those of deionized water and seawater immersed samples. A comparison of percent decreases in short beam shear strengths could not be made due to a large scatter in data. This may indicate defects in samples due to machining or variations in material properties due to processing.

  10. Automated detection, characterization, and tracking of filaments from SDO data

    NASA Astrophysics Data System (ADS)

    Buchlin, Eric; Vial, Jean-Claude; Mercier, Claude; Goujon, Jean-Baptiste

    Thanks to the cadence and continuity of AIA and HMI observations, SDO offers unique data for detecting, characterizing, and tracking solar filaments, until their eruptions, which are often associated with coronal mass ejections. Because of the requirement of short latency when aiming at space weather applications, and because of the important data volume, only an automated detection can be worked out. We present the code "FILaments, Eruptions, and Activations detected from Space" (FILEAS) that we have developed for the automated detection and tracking of filaments. Detections are based on the analysis of AIA 30.4 nm He II images and on the magnetic polarity inversion lines derived from HMI. Following the tracking of filaments as they rotate with the Sun, filament characteristics are computed and a database of filaments parameters is built. We present the algorithms and performances of the code, and we compare its results with the filaments detected in Halpha and already present in the Heliophysics Events Knowledgebase. We finally discuss the possibility of using such a code to detect eruptions in real time.

  11. Measuring the regulation of keratin filament network dynamics

    PubMed Central

    Moch, Marcin; Herberich, Gerlind; Aach, Til; Leube, Rudolf E.; Windoffer, Reinhard

    2013-01-01

    The organization of the keratin intermediate filament cytoskeleton is closely linked to epithelial function. To study keratin network plasticity and its regulation at different levels, tools are needed to localize and measure local network dynamics. In this paper, we present image analysis methods designed to determine the speed and direction of keratin filament motion and to identify locations of keratin filament polymerization and depolymerization at subcellular resolution. Using these methods, we have analyzed time-lapse fluorescence recordings of fluorescent keratin 13 in human vulva carcinoma-derived A431 cells. The fluorescent keratins integrated into the endogenous keratin cytoskeleton, and thereby served as reliable markers of keratin dynamics. We found that increased times after seeding correlated with down-regulation of inward-directed keratin filament movement. Bulk flow analyses further revealed that keratin filament polymerization in the cell periphery and keratin depolymerization in the more central cytoplasm were both reduced. Treating these cells and other human keratinocyte-derived cells with EGF reversed all these processes within a few minutes, coinciding with increased keratin phosphorylation. These results highlight the value of the newly developed tools for identifying modulators of keratin filament network dynamics and characterizing their mode of action, which, in turn, contributes to understanding the close link between keratin filament network plasticity and epithelial physiology. PMID:23757496

  12. Fragmentation and depolymerization of non-covalently bonded filaments.

    PubMed

    Zaccone, A; Terentjev, I; Di Michele, L; Terentjev, E M

    2015-03-21

    Protein molecules often self-assemble by means of non-covalent physical bonds to form extended filaments, such as amyloids, F-actin, intermediate filaments, and many others. The kinetics of filament growth is limited by the disassembly rate, at which inter-protein bonds break due to the thermal motion. Existing models often assume that the thermal dissociation of subunits occurs uniformly along the filament, or even preferentially in the middle, while the well-known propensity of F-actin to depolymerize from one end is mediated by biochemical factors. Here, we show for a very general (and generic) model, using Brownian dynamics simulations and theory, that the breakup location along the filament is strongly controlled by the asymmetry of the binding force about the minimum, as well as by the bending stiffness of the filament. We provide the basic connection between the features of the interaction potential between subunits and the breakup topology. With central-force (that is, fully flexible) bonds, the breakup rate is always maximum in the middle of the chain, whereas for semiflexible or stiff filaments this rate is either a minimum in the middle or flat. The emerging framework provides a unifying understanding of biopolymer fragmentation and depolymerization and recovers earlier results in its different limits. PMID:25796264

  13. Proper horizontal photospheric flows below an eruptive filament

    NASA Astrophysics Data System (ADS)

    Schmieder, Brigitte; Mein, Pierre; Mein, Nicole; Roudier, Thierry; Chandra, Ramseh

    An analysis of the proper motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track the granules as well as the large scale photospheric flows, was perfomed during three hours in a region containing a large filament channel on September 17, 2010. Supergranules were idenfied in the filament channel. Diverging flows inside the supergranules are similar in and out the filament channel. Using corks, we derived the passive scalar points and produced maps of cork distribution. The anchorage structures with the photosphere (feet) of the filament are located in the areas of converging flows with accumulations of corks. Averaging the velocity vectors for each latitude we defined a profile of the differential rotation. We conclude that the coupling between the convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its feet. On a large scale point-of-view the differential rotation induced a shear of 0.1 km/s in the filament. On a small scale point-of-view convection motions favored the interaction/cancellation of the parasitic polarities at the base of the feet with the surrounding network explaining the brightenings,/jets and the eruption that were observed in the EUV filament.

  14. A nebulin ruler does not dictate thin filament lengths.

    PubMed

    Castillo, Angelica; Nowak, Roberta; Littlefield, Kimberly P; Fowler, Velia M; Littlefield, Ryan S

    2009-03-01

    To generate force, striated muscle requires overlap between uniform-length actin and myosin filaments. The hypothesis that a nebulin ruler mechanism specifies thin filament lengths by targeting where tropomodulin (Tmod) caps the slow-growing, pointed end has not been rigorously tested. Using fluorescent microscopy and quantitative image analysis, we found that nebulin extended 1.01-1.03 mum from the Z-line, but Tmod localized 1.13-1.31 mum from the Z-line, in seven different rabbit skeletal muscles. Because nebulin does not extend to the thin filament pointed ends, it can neither target Tmod capping nor specify thin filament lengths. We found instead a strong correspondence between thin filament lengths and titin isoform sizes for each muscle. Our results suggest the existence of a mechanism whereby nebulin specifies the minimum thin filament length and sarcomere length regulates and coordinates pointed-end dynamics to maintain the relative overlap of the thin and thick filaments during myofibril assembly. PMID:19254544

  15. Star-forming filaments in warm dark matter models

    NASA Astrophysics Data System (ADS)

    Gao, Liang; Theuns, Tom; Springel, Volker

    2015-06-01

    We performed a hydrodynamical cosmological simulation of the formation of a Milky Way-like galaxy in a warm dark matter (WDM) cosmology. Smooth and dense filaments, several comoving mega parsec long, form generically above z ˜ 2 in this model. Atomic line cooling allows gas in the centres of these filaments to cool to the base of the cooling function, resulting in a very striking pattern of extended Lyman-limit systems (LLSs). Observations of the correlation function of LLSs might hence provide useful limits on the nature of the dark matter. We argue that the self-shielding of filaments may lead to a thermal instability resulting in star formation. We implement a sub-grid model for this, and find that filaments rather than haloes dominate star formation until z ˜ 6, although this depends on how stars form in WDM. Reionization decreases the gas density in filaments, and the more usual star formation in haloes dominates below z ˜ 6, although star formation in filaments continues until z = 2. 15 per cent of the stars of the z = 0 galaxy formed in filaments. At higher redshift, these stars give galaxies a stringy appearance, which, if observed, might be a strong indication that the dark matter is warm.

  16. Geometry and Optimal Packing of Twisted Columns and Filaments

    E-print Network

    Gregory M. Grason

    2015-01-30

    This review presents recent progress in understanding constraints and consequences of close-packing geometry of filamentous or columnar materials possessing non-trivial textures, focusing in particular on the common motifs of twisted and toroidal structures. The mathematical framework is presented that relates spacing between line-like, filamentous elements to their backbone orientations, highlighting the explicit connection between the inter-filament {\\it metric} properties and the geometry of non-Euclidean surfaces. The consequences of the hidden connection between packing in twisted filament bundles and packing on positively curved surfaces, like the Thomson problem, are demonstrated for the defect-riddled ground states of physical models of twisted filament bundles. The connection between the "ideal" geometry of {\\it fibrations} of curved three-dimensional space, including the Hopf fibration, and the non-Euclidean constraints of filament packing in twisted and toroidal bundles is presented, with a focus on the broader dependence of metric geometry on the simultaneous twisting and folded of multi-filament bundles.

  17. The Size Distribution of Void Filaments in a LCDM Cosmology

    E-print Network

    Daeseong Park; Jounghun Lee

    2009-05-20

    The size distribution of mini-filaments in voids has been derived from the Millennium Run halo catalogs at redshifts z=0,0.5,1 and 2. It is assumed that the primordial tidal field originated the presence of filamentary substructures in voids and that the void filaments have evolved only little, keeping the initial memory of the primordial tidal field. Applying the filament-finding algorithm based on the minimal spanning tree (MST) technique to the Millennium voids, we identify the mini-filaments running through voids and measure their sizes at each redshift. Then, we calculate the comoving number density of void filaments as a function of their sizes in the logarithmic interval and determine an analytic fitting function for it. It is found that the size distribution of void mini-filaments in the logarithmic interval has an almost universal shape, insensitive to the redshift: In the short-size section it is well approximated as a power-law, while in the long-size section it decreases exponentially. We expect that the universal size distribution of void filaments may provide a useful cosmological probe without resorting to the rms density fluctuations.

  18. Abstract--This paper proposes a methodology to decide the optimal matching between the size of the rotor of a wind turbine

    E-print Network

    Paris-Sud XI, Université de

    of the rotor of a wind turbine and the rated power of a permanent magnet synchronous machine. This is made of the wind turbine, the gearbox's transformation ratio, the battery voltage and the wind speed probability's rated power and the wind turbine's rotor size. The system studied in this paper consists of 220 (V)/50

  19. Large-scale filaments associated with Milky Way spiral arms

    NASA Astrophysics Data System (ADS)

    Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, C. Malcolm; Molinari, Sergio; Schisano, Eugenio

    2015-07-01

    The ubiquity of filamentary structure at various scales throughout the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large-scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e. as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel Hi-GAL (Herschel Infrared Galactic Plane Survey) data complemented by spectral line cubes. We present a sample of the nine most prominent Herschel filaments, including six identified from a pilot search field plus three from outside the field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3) × 104 M?, and beam-averaged (28 arcsec, or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)× 1022 cm- 2. The bulk of the filaments are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K. All the filaments are located within ?60 pc from the Galactic mid-plane. Comparing the filaments to a recent spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These filaments are comparable in length to the Galactic scaleheight and therefore are not simply part of a grander turbulent cascade.

  20. Characterizing interstellar filaments with Herschel in nearby molecular clouds

    NASA Astrophysics Data System (ADS)

    Arzoumanian, D.; André, P.; Peretto, N.; Könyves, V.; Schneider, N.; Didelon, P.; Palmeirim, P.

    2012-03-01

    Herschel observations of molecular clouds reveal the presence of complex filamentary structures which are shown to be the main sites of core and protostar formation (André et al. 2010). Understanding the properties of these filaments is a first step toward establishing a broader scenario of star formation in the Galaxy. Thanks to their unprecedented spatial dynamic range in the submillimeter regime, the Herschel images provide detailed quantitative information on these filaments, making it possible to characterize their properties in a statistical manner (Arzoumanian et al. 2011). I will discuss the properties of filaments seen by Herschel in 5 regions from the Gould Belt survey (IC5146, Aquila, Pipe, Taurus, Polaris), located at distances from 150 pc to 460 pc and having different star formation activities (filaments with column densities from ˜ 1020 cm-2 in Polaris to >1023 cm-2 in Aquila). The radial density profiles of the filaments show a power-law behavior at large radii of r-2 (shallower than the hydrostatic isothermal Ostriker model described by ? ˜ r-4 ) with a flat inner part, which is remarkably uniform (˜ 0.1 pc ) for all filaments in our sample (˜ 150 filaments) regardless of column density. The observed filaments are not strictly isothermal, their dust temperature profiles show a slight (˜ 3K) but significant decrease in temperature toward the center. I will complement the analysis based on Herschel with preliminary line-width measurements with the IRAM 30m telescope. We find evidence of an increase in non-thermal velocity dispersion with column density, denser filaments being more turbulent than more diffuse ones (Arzoumanian et al. in prep.).