Study of the AC machines winding having fractional q

NASA Astrophysics Data System (ADS)

Bespalov, V. Y.; Sidorov, A. O.

2018-02-01

The winding schemes with a fractional numbers of slots per pole and phase q have been known and used for a long time. However, in the literature on the low-noise machines design there are not recommended to use. Nevertheless, fractional q windings have been realized in many applications of special AC electrical machines, allowing to improve their performance, including vibroacoustic one. This paper deals with harmonic analysis of windings having integer and fractional q in permanent magnet synchronous motors, a comparison of their characteristics is performed, frequencies of subharmonics are revealed. Optimal winding pitch design is found giving reduce the amplitudes of subharmonics. Distribution factors for subharmonics, fractional and high-order harmonics are calculated, results analysis is represented, allowing for giving recommendations how to calculate distribution factors for different harmonics when q is fractional.

Variable cross-section windings for efficiency improvement of electric machines

NASA Astrophysics Data System (ADS)

Grachev, P. Yu; Bazarov, A. A.; Tabachinskiy, A. S.

2018-02-01

Implementation of energy-saving technologies in industry is impossible without efficiency improvement of electric machines. The article considers the ways of efficiency improvement and mass and dimensions reduction of electric machines with electronic control. Features of compact winding design for stators and armatures are described. Influence of compact winding on thermal and electrical process is given. Finite element method was used in computer simulation.

Multi-winding homopolar electric machine

DOEpatents

Van Neste, Charles W

2012-10-16

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

Superconducting Coil Winding Machine Control System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nogiec, J. M.; Kotelnikov, S.; Makulski, A.

The Spirex coil winding machine is used at Fermilab to build coils for superconducting magnets. Recently this ma-chine was equipped with a new control system, which al-lows operation from both a computer and a portable remote control unit. This control system is distributed between three layers, implemented on a PC, real-time target, and FPGA, providing respectively HMI, operational logic and direct controls. The system controls motion of all mechan-ical components and regulates the cable tension. Safety is ensured by a failsafe, redundant system.

Permanent magnet machine with windings having strand transposition

DOEpatents

Qu, Ronghai; Jansen, Patrick Lee

2009-04-21

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

Filament winding cylinders. II - Validation of the process model

NASA Technical Reports Server (NTRS)

Calius, Emilio P.; Lee, Soo-Yong; Springer, George S.

1990-01-01

Analytical and experimental studies were performed to validate the model developed by Lee and Springer for simulating the manufacturing process of filament wound composite cylinders. First, results calculated by the Lee-Springer model were compared to results of the Calius-Springer thin cylinder model. Second, temperatures and strains calculated by the Lee-Springer model were compared to data. The data used in these comparisons were generated during the course of this investigation with cylinders made of Hercules IM-6G/HBRF-55 and Fiberite T-300/976 graphite-epoxy tows. Good agreement was found between the calculated and measured stresses and strains, indicating that the model is a useful representation of the winding and curing processes.

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…

Stator for a rotating electrical machine having multiple control windings

DOEpatents

Shah, Manoj R.; Lewandowski, Chad R.

2001-07-17

A rotating electric machine is provided which includes multiple independent control windings for compensating for rotor imbalances and for levitating/centering the rotor. The multiple independent control windings are placed at different axial locations along the rotor to oppose forces created by imbalances at different axial locations along the rotor. The multiple control windings can also be used to levitate/center the rotor with a relatively small magnetic field per unit area since the rotor and/or the main power winding provides the bias field.

Calculating Synchronous Inductive Reactances of Contactless Machines When Magnetic Circuit is Saturated and of Machines with Superconducting Excitation Windings,

DTIC Science & Technology

The work studies the effect of magnetic circuit saturation on the synchronous inductive reactance of the armature. A practical method is given for...calculating synchronized parameters in saturating synchronized machines with additional clearances and machines with superconducting excitation windings.

Filament Winding Multifunctional Carbon Nanotube Composites of Various Dimensionality

NASA Astrophysics Data System (ADS)

Wells, Brian David

Carbon nanotubes (CNT) have been long considered an optimal material for composites due to their high strength, high modulus, and electrical/thermal conductivity. These composite materials have the potential to be used in the aerospace, computer, automotive, medical industry as well as many others. The nano dimensions of these structures make controlled alignment and distribution difficult using many production techniques. An area that shows promise for controlled alignment is the formation of CNT yarns. Different approaches have been used to create yarns with various winding angles and diameters. CNTs resemble traditional textile fiber structures due to their one-dimensional dimensions, axial strength and radial flexibility. One difference is, depending on the length, CNTs can have aspect ratios that far exceed those of traditional textile fibers. This can complicate processing techniques and cause agglomeration which prevents optimal structures from being created. However, with specific aspect ratios and spatial distributions a specific type of CNT, vertically aligned spinnable carbon nanotubes (VASCNTs), have interesting properties that allow carbon nanotubes to be drawn from an array in a continuous aligned web. This dissertation examines the feasibility of combining VASCNTs with another textile manufacturing process, filament winding, to create structures with various levels of dimensionality. While yarn formation with CNTs has been largely studied, there has not been significant work studying the use of VASCNTs to create composite materials. The studies that have been produces revolve around mixing CNTs into epoxy or creating uni-directional wound structures. In this dissertation VASCNTs are used to create filament wound materials with various degrees of alignment. These structures include 1 dimensional coatings applied to non-conductive polymer monofilaments, two dimensional multifunctional adhesive films, and three dimensional hybrid-nano composites. The

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

NASA Astrophysics Data System (ADS)

Gündoğdu, 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.

ACQUA: Automated Cyanobacterial Quantification Algorithm for toxic filamentous genera using spline curves, pattern recognition and machine learning.

PubMed

Gandola, Emanuele; Antonioli, Manuela; Traficante, Alessio; Franceschini, Simone; Scardi, Michele; Congestri, Roberta

2016-05-01

Toxigenic cyanobacteria are one of the main health risks associated with water resources worldwide, as their toxins can affect humans and fauna exposed via drinking water, aquaculture and recreation. Microscopy monitoring of cyanobacteria in water bodies and massive growth systems is a routine operation for cell abundance and growth estimation. Here we present ACQUA (Automated Cyanobacterial Quantification Algorithm), a new fully automated image analysis method designed for filamentous genera in Bright field microscopy. A pre-processing algorithm has been developed to highlight filaments of interest from background signals due to other phytoplankton and dust. A spline-fitting algorithm has been designed to recombine interrupted and crossing filaments in order to perform accurate morphometric analysis and to extract the surface pattern information of highlighted objects. In addition, 17 specific pattern indicators have been developed and used as input data for a machine-learning algorithm dedicated to the recognition between five widespread toxic or potentially toxic filamentous genera in freshwater: Aphanizomenon, Cylindrospermopsis, Dolichospermum, Limnothrix and Planktothrix. The method was validated using freshwater samples from three Italian volcanic lakes comparing automated vs. manual results. ACQUA proved to be a fast and accurate tool to rapidly assess freshwater quality and to characterize cyanobacterial assemblages in aquatic environments. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface wind characteristics of some Aleutian Islands. [for selection of windpowered machine sites

NASA Technical Reports Server (NTRS)

Wentink, T., Jr.

1973-01-01

The wind power potential of Alaska is assessed in order to determine promising windpower sites for construction of wind machines and for shipment of wind derived energy. Analyses of near surface wind data from promising Aleutian sites accessible by ocean transport indicate probable velocity regimes and also present deficiencies in available data. It is shown that winds for some degree of power generation are available 77 percent of the time in the Aleutians with peak velocities depending on location.

Winding Schemes for Wide Constant Power Range of Double Stator Transverse Flux Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hassan, Iftekhar; Sozer, Yilmaz

2015-05-01

Different ring winding schemes for double sided transverse flux machines are investigated in this paper for wide speed operation. The windings under investigation are based on two inverters used in parallel. At higher power applications this arrangement improves the drive efficiency. The new winding structure through manipulation of the end connection splits individual sets into two and connects the partitioned turns from individual stator sets in series. This configuration offers the flexibility of torque profiling and a greater flux weakening region. At low speeds and low torque only one winding set is capable of providing the required torque thus providingmore » greater fault tolerance. At higher speeds one set is dedicated to torque production and the other for flux control. The proposed method improves the machine efficiency and allows better flux weakening which is desirable for traction applications.« less

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.

Dynamics of a single flexible filament in a flowing soap film

NASA Astrophysics Data System (ADS)

Chen, Chaonan; Feng, Shunshan; Zhou, Tong

2016-11-01

The interactions between flexible plates and surrounding fluids like two-dimensional flag-in-wind problems are important physical phenomena. Here we use a spandex filament with one end fixed flapping in gravity-driven soap film device which can be regarded as a quasi-two-dimensional flow tunnel. A silk filament had been used previously to demonstrate three stable dynamical states: stretched-straight, flapping, and bistable states. The similar phenomena occured for a spandex filament while the bifurcation conditions seem to be different compared with a silk filament, as the critical filament length is longer and critical inflow velocity is higher than that for a silk filament. In the experiment, we considered some representative parameters (filament length, inflow velocity, and bending stiffness of the filament) to study their effects on the stability of the filament and its bifurcation conditions. An interface-tracking ALE finite element method was then conducted to reproduce the experiment and investigate more details about effects of these parameters. which are significant to reveal the underlying mechanism of flag-in-wind problem. Corresponding Author. Email:zhoutong@bit.edu.cn.

Formation and evolution of magnetised filaments in wind-swept turbulent clumps

NASA Astrophysics Data System (ADS)

Banda-Barragan, Wladimir Eduardo; Federrath, Christoph; Crocker, Roland M.; Bicknell, Geoffrey Vincent; Parkin, Elliot Ross

2015-08-01

Using high-resolution three-dimensional simulations, we examine the formation and evolution of filamentary structures arising from magnetohydrodynamic interactions between supersonic winds and turbulent clumps in the interstellar medium. Previous numerical studies assumed homogenous density profiles, null velocity fields, and uniformly distributed magnetic fields as the initial conditions for interstellar clumps. Here, we have, for the first time, incorporated fractal clumps with log-normal density distributions, random velocity fields and turbulent magnetic fields (superimposed on top of a uniform background field). Disruptive processes, instigated by dynamical instabilities and akin to those observed in simulations with uniform media, lead to stripping of clump material and the subsequent formation of filamentary tails. The evolution of filaments in uniform and turbulent models is, however, radically different as evidenced by comparisons of global quantities in both scenarios. We show, for example, that turbulent clumps produce tails with higher velocity dispersions, increased gas mixing, greater kinetic energy, and lower plasma beta than their uniform counterparts. We attribute the observed differences to: 1) the turbulence-driven enhanced growth of dynamical instabilities (e.g. Kelvin-Helmholtz and Rayleigh-Taylor instabilities) at fluid interfaces, and 2) the localised amplification of magnetic fields caused by the stretching of field lines trapped in the numerous surface deformations of fractal clumps. We briefly discuss the implications of this work to the physics of the optical filaments observed in the starburst galaxy M82.

Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

NASA Astrophysics Data System (ADS)

Veronesi, F.; Grassi, S.

2016-09-01

Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners.

Two Machine Learning Approaches for Short-Term Wind Speed Time-Series Prediction.

PubMed

Ak, Ronay; Fink, Olga; Zio, Enrico

2016-08-01

The increasing liberalization of European electricity markets, the growing proportion of intermittent renewable energy being fed into the energy grids, and also new challenges in the patterns of energy consumption (such as electric mobility) require flexible and intelligent power grids capable of providing efficient, reliable, economical, and sustainable energy production and distribution. From the supplier side, particularly, the integration of renewable energy sources (e.g., wind and solar) into the grid imposes an engineering and economic challenge because of the limited ability to control and dispatch these energy sources due to their intermittent characteristics. Time-series prediction of wind speed for wind power production is a particularly important and challenging task, wherein prediction intervals (PIs) are preferable results of the prediction, rather than point estimates, because they provide information on the confidence in the prediction. In this paper, two different machine learning approaches to assess PIs of time-series predictions are considered and compared: 1) multilayer perceptron neural networks trained with a multiobjective genetic algorithm and 2) extreme learning machines combined with the nearest neighbors approach. The proposed approaches are applied for short-term wind speed prediction from a real data set of hourly wind speed measurements for the region of Regina in Saskatchewan, Canada. Both approaches demonstrate good prediction precision and provide complementary advantages with respect to different evaluation criteria.

Two Capacitive Micro-Machined Ultrasonic Transducers for Wind Speed Measurement

PubMed Central

Bui, Gia Thinh; Jiang, Yu-Tsung; Pang, Da-Chen

2016-01-01

This paper presents a new wind speed measurement method using a single capacitive micro-machined ultrasonic transducer (CMUT). The CMUT was arranged perpendicular to the direction of the wind flow, and a reflector was set up a short distance away, facing the CMUT. To reduce the size, weight, cost, and power consumption of conventional ultrasonic anemometers this study proposes two CMUT designs for the measurement of wind speed using either the amplitude of the signal or the time of flight (TOF). Each CMUT with a double array element design can transmit and receive signals in five different operation modes. Experiments showed that the two CMUT designs utilizing the TOF were better than those utilizing the amplitude of the signal for wind speed measurements ranging from 1 m/s to 10 m/s, providing a measurement error of less than 0.2 m/s. These results indicate that the sensitivity of the TOF is independent of the five operation modes. PMID:27271625

Two Capacitive Micro-Machined Ultrasonic Transducers for Wind Speed Measurement.

PubMed

Bui, Gia Thinh; Jiang, Yu-Tsung; Pang, Da-Chen

2016-06-02

This paper presents a new wind speed measurement method using a single capacitive micro-machined ultrasonic transducer (CMUT). The CMUT was arranged perpendicular to the direction of the wind flow, and a reflector was set up a short distance away, facing the CMUT. To reduce the size, weight, cost, and power consumption of conventional ultrasonic anemometers this study proposes two CMUT designs for the measurement of wind speed using either the amplitude of the signal or the time of flight (TOF). Each CMUT with a double array element design can transmit and receive signals in five different operation modes. Experiments showed that the two CMUT designs utilizing the TOF were better than those utilizing the amplitude of the signal for wind speed measurements ranging from 1 m/s to 10 m/s, providing a measurement error of less than 0.2 m/s. These results indicate that the sensitivity of the TOF is independent of the five operation modes.

Impact of equalizing currents on losses and torque ripples in electrical machines with fractional slot concentrated windings

NASA Astrophysics Data System (ADS)

Toporkov, D. M.; Vialcev, G. B.

2017-10-01

The implementation of parallel branches is a commonly used manufacturing method of the realizing of fractional slot concentrated windings in electrical machines. If the rotor eccentricity is enabled in a machine with parallel branches, the equalizing currents can arise. The simulation approach of the equalizing currents in parallel branches of an electrical machine winding based on magnetic field calculation by using Finite Elements Method is discussed in the paper. The high accuracy of the model is provided by the dynamic improvement of the inductances in the differential equation system describing a machine. The pre-computed table flux linkage functions are used for that. The functions are the dependences of the flux linkage of parallel branches on the branches currents and rotor position angle. The functions permit to calculate self-inductances and mutual inductances by partial derivative. The calculated results obtained for the electric machine specimen are presented. The results received show that the adverse combination of design solutions and the rotor eccentricity leads to a high value of the equalizing currents and windings heating. Additional torque ripples also arise. The additional ripples harmonic content is not similar to the cogging torque or ripples caused by the rotor eccentricity.

Hygrothermomechanical evaluation of transverse filament tape epoxy/polyester fiberglass composites

NASA Technical Reports Server (NTRS)

Lark, R. F.; Chamis, C. C.

1984-01-01

Transverse filament tape (TFT) fiberglass/epoxy and TFT polyester composites intended for low cost wind turbine blade fabrication have been subjected to static and cyclic load behavior tests whose results are presently evaluated on the basis of an integrated hygrothermomechanical response theory. Laminate testing employed simulated filament winding procedures. The results obtained show that the predicted hygrothermomechanical environmental effects on TFT composites are in good agreement with measured data for various properties, including fatigue at different R-ratio values.

Graphite filament wound pressure vessels

NASA Technical Reports Server (NTRS)

Feldman, A.; Damico, J. J.

1972-01-01

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

Method for preparing metallated filament-wound structures

DOEpatents

Peterson, George R.

1979-01-01

Metallated graphite filament-wound structures are prepared by coating a continuous multi-filament carbon yarn with a metal carbide, impregnating the carbide coated yarn with a polymerizable carbon precursor, winding the resulting filament about a mandrel, partially curing the impregnation in air, subjecting the wound composite to heat and pressure to cure the carbon precursor, and thereafter heating the composite in a sizing die at a pressure loading of at least 1000 psi for graphitizing the carbonaceous material in the composite. The carbide in the composite coalesces into rod-like shapes which are disposed in an end-to-end relationship parallel with the filaments to provide resistance to erosion in abrasive laden atmospheres.

Protein machines and self assembly in muscle organization

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

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

ERIC Educational Resources Information Center

Michigan Univ., Ann Arbor.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlin, P.W.

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

Modelling the Peak Elongation of Nylon6 and Fe Powder Based Composite Wire for FDM Feedstock Filament

NASA Astrophysics Data System (ADS)

Garg, Harish Kumar; Singh, Rupinder

2017-10-01

In the present work, to increase the application domain of fused deposition modelling (FDM) process, Nylon6-Fe powder based composite wire has been prepared as feed stock filament. Further for smooth functioning of feed stock filament without any change in the hardware and software of the commercial FDM setup, the mechanical properties of the newly prepared composite wire must be comparable/at par to the existing material i.e. ABS, P-430. So, keeping this in consideration; an effort has been made to model the peak elongation of in house developed feedstock filament comprising of Nylon6 and Fe powder (prepared on single screw extrusion process) for commercial FDM setup. The input parameters of single screw extruder (namely: barrel temperature, temperature of the die, speed of the screw, speed of the winding machine) and rheological property of material (melt flow index) has been modelled with peak elongation as the output by using response surface methodology. For validation of model the result of peak elongation obtained from the model equation the comparison was made with the results of actual experimentation which shows the variation of ±1 % only.

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.

Structural CNT Composites. Part I; Developing a Carbon Nanotube Filament Winder

NASA Technical Reports Server (NTRS)

Sauti, Godfrey; Kim, Jae-Woo; Wincheski, Russell A.; Antczak, Andrew; Campero, Jamie C.; Luong, Hoa H.; Shanahan, Michelle H.; Stelter, Christopher J.; Siochi, Emilie J.

2015-01-01

Carbon nanotube (CNT) based materials promise advances in the production of high strength and multifunctional components for aerospace and other applications. Specifically, in tension dominated applications, the latest CNT based filaments are yielding composite properties comparable to or exceeding composites from more established fibers such as Kevlar and carbon fiber. However, for the properties of these materials to be fully realized at the component level, suitable manufacturing processes have to be developed. These materials handle differently from conventional fibers, with different wetting characteristics and behavior under load. The limited availability of bulk forms also requires that the equipment be scaled down accordingly to tailor the process development approach to material availability. Here, the development of hardware and software for filament winding of carbon nanotube based tapes and yarns is described. This hardware features precision guidance of the CNT material and control of the winding tension over a wide range in an open architecture that allows for effective process control and troubleshooting during winding. Use of the filament winder to develop CNT based Composite Overwrapped Pressure Vessels (COPVs) shall also be discussed.

Filament Advance Detection Sensor for Fused Deposition Modelling 3D Printers

PubMed Central

Islán Marcos, Manuel

2018-01-01

The main purpose of this paper is to present a system to detect extrusion failures in fused deposition modelling (FDM) 3D printers by sensing that the filament is moving forward properly. After several years using these kind of machines, authors detected that there is not any system to detect the main problem in FDM machines. Authors thought in different sensors and used the weighted objectives method, one of the most common evaluation methods, for comparing design concepts based on an overall value per design concept. Taking into account the obtained scores of each specification, the best choice for this work is the optical encoder. Once the sensor is chosen, it is necessary to design de part where it will be installed without interfering with the normal function of the machine. To do it, photogrammetry scanning methodology was employed. The developed device perfectly detects the advance of the filament without affecting the normal operation of the machine. Also, it is achieved the primary objective of the system, avoiding loss of material, energy, and mechanical wear, keeping the premise of making a low-cost product that does not significantly increase the cost of the machine. This development has made it possible to use the printer with remains of coil filaments, which were not spent because they were not sufficient to complete an impression. Also, printing models in two colours with only one extruder has been enabled by this development. PMID:29747458

Filament Advance Detection Sensor for Fused Deposition Modelling 3D Printers.

PubMed

Soriano Heras, Enrique; Blaya Haro, Fernando; de Agustín Del Burgo, José M; Islán Marcos, Manuel; D'Amato, Roberto

2018-05-09

The main purpose of this paper is to present a system to detect extrusion failures in fused deposition modelling (FDM) 3D printers by sensing that the filament is moving forward properly. After several years using these kind of machines, authors detected that there is not any system to detect the main problem in FDM machines. Authors thought in different sensors and used the weighted objectives method, one of the most common evaluation methods, for comparing design concepts based on an overall value per design concept. Taking into account the obtained scores of each specification, the best choice for this work is the optical encoder. Once the sensor is chosen, it is necessary to design de part where it will be installed without interfering with the normal function of the machine. To do it, photogrammetry scanning methodology was employed. The developed device perfectly detects the advance of the filament without affecting the normal operation of the machine. Also, it is achieved the primary objective of the system, avoiding loss of material, energy, and mechanical wear, keeping the premise of making a low-cost product that does not significantly increase the cost of the machine. This development has made it possible to use the printer with remains of coil filaments, which were not spent because they were not sufficient to complete an impression. Also, printing models in two colours with only one extruder has been enabled by this development.

Pole-phase modulated toroidal winding for an induction machine

DOEpatents

Miller, John Michael; Ostovic, Vlado

1999-11-02

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

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.

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.

Wind power machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denehi, D.

1992-07-28

This patent describes wind powered apparatus for producing electricity. It comprises: an endless chain trained over and movable in a continuous path about two substantially spaced-apart sprockets, a plurality of sails fixedly attached to the chain, guide means positioned adjacent the chain and operable, a rotary electrical generator; means connecting at least one of the sprockets to the generator to rotate the latter in response to movement of the chain by wind acting upon the sail flaps when in the first, open position thereof.

Fatigue testing of low-cost fiberglass composite wind turbine blade materials

NASA Technical Reports Server (NTRS)

Hofer, K. E.; Bennett, L. C.

1981-01-01

The static and fatigue behavior of transverse filament tape (TFT) fiberglass/epoxy and TFT/polyester composites was established by the testing of specimens cut from panels fabricated by a filament winding process used for the construction of large experimental wind turbine blades.

Development of the WTS-4 wind turbine design

NASA Astrophysics Data System (ADS)

Hasbrouck, T. M.; Divalentin, E.

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

Observations of the Growth of an Active Region Filament

NASA Astrophysics Data System (ADS)

Yang, Bo

2017-04-01

We present observations of the growth of an active region filament caused by magnetic interactions among the filament and its adjacent superpenumbral filament (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the filament is the first step reconnection, which resulted in the filament bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to the disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the filament and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed filament threads, appeared. Hαobservations show that this twisted structure is a longer sinistral filament. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the filament consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among filaments and their adjacent SFs and T could lead to the growth of the filaments, and the filament is probably supported in a flux rope.

OBSERVATIONS OF THE GROWTH OF AN ACTIVE REGION FILAMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Bo; Jiang, Yunchun; Yang, Jiayan

We present observations of the growth of an active region filament caused by magnetic interactions among the filament and its adjacent superpenumbral filament (SF) and dark thread-like structures (T). Multistep reconnections are identified during the whole growing process. Magnetic flux convergence and cancellation occurring at the positive footpoint region of the filament is the first step reconnection, which resulted in the filament bifurcating into two sets of intertwined threads. One set anchored in situ, while the other set moved toward and interacted with the SF and part of T. This indicates the second step reconnection, which gave rise to themore » disappearance of the SF and the formation of a long thread-like structure that connects the far ends of the filament and T. The long thread-like structure further interacted with the T and then separated into two parts, representing the third step reconnection. Finally, another similar long thread-like structure, which intertwined with the fixed filament threads, appeared. H {sub α} observations show that this twisted structure is a longer sinistral filament. Based on the observed photospheric vector magnetograms, we performed a non-linear force-free field extrapolation to reconstruct the magnetic fields above the photosphere and found that the coronal magnetic field lines associated with the filament consists of two twisted flux ropes winding around each other. These results suggest that magnetic interactions among filaments and their adjacent SFs and T could lead to the growth of the filaments, and the filament is probably supported in a flux rope.« less

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.

Induction machine

DOEpatents

Owen, Whitney H.

1980-01-01

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

Liquid oxygen-compatible filament-winding matrix resin

NASA Technical Reports Server (NTRS)

Harrison, E. S.

1973-01-01

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

Wind at Work.

ERIC Educational Resources Information Center

Adams, Stephen

1998-01-01

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

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.

Fine modeling of reinforced thermoplastic filament winding container

NASA Astrophysics Data System (ADS)

Duan, Chenghong; Huang, Jinhao; Wu, Liang; Luo, Xiangpeng

2018-05-01

Reinforced thermoplastic containers has been widely used because of its corrosion-resistant, fatigue-resistant features. The characteristics of the liner and wound layer material and the different winding methods lead to the fact that the model obtained according to the ordinary pressure vessel modeling method does not reflect the actual situation of the reinforced thermoplastic container. In this paper, the thickness of stratified winding was calculated based on the principle of constant fiber total volume and equal cross-sectional area. ANSYS ACP module was used to refine the full winding container and provide a reference for engineering simulation solution.

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

NASA Astrophysics Data System (ADS)

Hsu, Ming-Chen; Bazilevs, Yuri

2012-12-01

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

Non-conventional rule of making a periodically varying different-pole magnetic field in low-power alternating current electrical machines with using ring coils in multiphase armature winding

NASA Astrophysics Data System (ADS)

Plastun, A. T.; Tikhonova, O. V.; Malygin, I. V.

2018-02-01

The paper presents methods of making a periodically varying different-pole magnetic field in low-power electrical machines. Authors consider classical designs of electrical machines and machines with ring windings in armature, structural features and calculated parameters of magnetic circuit for these machines.

High speed operation of permanent magnet machines

NASA Astrophysics Data System (ADS)

El-Refaie, Ayman M.

This work proposes methods to extend the high-speed operating capabilities of both the interior PM (IPM) and surface PM (SPM) machines. For interior PM machines, this research has developed and presented the first thorough analysis of how a new bi-state magnetic material can be usefully applied to the design of IPM machines. Key elements of this contribution include identifying how the unique properties of the bi-state magnetic material can be applied most effectively in the rotor design of an IPM machine by "unmagnetizing" the magnet cavity center posts rather than the outer bridges. The importance of elevated rotor speed in making the best use of the bi-state magnetic material while recognizing its limitations has been identified. For surface PM machines, this research has provided, for the first time, a clear explanation of how fractional-slot concentrated windings can be applied to SPM machines in order to achieve the necessary conditions for optimal flux weakening. A closed-form analytical procedure for analyzing SPM machines designed with concentrated windings has been developed. Guidelines for designing SPM machines using concentrated windings in order to achieve optimum flux weakening are provided. Analytical and numerical finite element analysis (FEA) results have provided promising evidence of the scalability of the concentrated winding technique with respect to the number of poles, machine aspect ratio, and output power rating. Useful comparisons between the predicted performance characteristics of SPM machines equipped with concentrated windings and both SPM and IPM machines designed with distributed windings are included. Analytical techniques have been used to evaluate the impact of the high pole number on various converter performance metrics. Both analytical techniques and FEA have been used for evaluating the eddy-current losses in the surface magnets due to the stator winding subharmonics. Techniques for reducing these losses have been

Development of cryogenic PRD-49-1 filament-wound tanks

NASA Technical Reports Server (NTRS)

Hoggatt, J. T.

1971-01-01

A high modulus polymeric fiber was evaluated as a reinforcement for filament wound pressure vessels. Winding parameters and design data were established for the fiber with two different epoxy resin systems. Comparison was made between the performance factors of the polymeric fiber and those of S-glass and high modulus graphite vessels.

Filament Eruptions, Jets, and Space Weather

NASA Technical Reports Server (NTRS)

Moore, Ronald; Sterling, Alphonse; Robe, Nick; Falconer, David; Cirtain, Jonathan

2013-01-01

-plasma component of coronal X-ray jets. This favors the idea that Type-II spicules are miniature counterparts of coronal X-ray jets. In Moore et al (2011, ApJ, 731, L18), we pointed out that if Type-II spicules are magnetic eruptions that work like coronal X-ray jets, they carry an area-averaged mechanical energy flux of approximately 7x10)(exp 5) erg cm(exp -2) s(exp-1) into the corona in the form of MHD waves and jet outflow, enough to power the heating of the global corona and solar wind. On this basis, from our observations of mini-filament eruptions in blowout X-ray jets, we infer that magnetic explosions of the type that have erupting filaments in them are the main engines of both (1) the steady solar wind and (2) the CMEs that produce the most severe space weather by blasting out through the corona and solar wind, making solar energetic particle storms, and bashing the Earth's magnetosphere. We conclude that in focusing on prominences and filament eruptions, Einar had his eye on the main bet for understanding what powers all space weather, both the extreme and the normal.

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.

380 kW synchronous machine with HTS rotor windings--development at Siemens and first test results

NASA Astrophysics Data System (ADS)

Nick, W.; Nerowski, G.; Neumüller, H.-W.; Frank, M.; van Hasselt, P.; Frauenhofer, J.; Steinmeyer, F.

2002-08-01

Applying HTS conductors in the rotor of synchronous machines allows the design of future motors or generators that are lighter, more compact and feature an improved coefficient of performance. To address these goals a project collaboration was installed within Siemens, including Automation & Drives, Large Drives as a leading supplier of electrical machines, Corporate Technology as a competence center for superconducting technology, and other partners. The main task of the project was to demonstrate the feasibility of basic concepts. The rotor was built from racetrack coils of Bi-2223 HTS tape conductor, these were assembled on a core and fixed by a bandage of glass-fibre composite. Rotor coil cooling is performed by thermal conduction, one end of the motor shaft is hollow to give access for the cooling system. Two cooling systems were designed and operated successfully: firstly an open circuit using cold gaseous helium from a storage vessel, but also a closed circuit system based on a cryogenerator. To take advantage of the increased rotor induction levels the stator winding was designed as an air gap winding. This was manufactured and fitted in a standard motor housing. After assembling of the whole system in a test facility with a DC machine load experiments have been started to prove the validity of our design, including operation with both cooling systems and driving the stator from the grid as well as by a power inverter.

Morphology of Pseudostreamers and Solar Wind Properties

NASA Astrophysics Data System (ADS)

Panasenco, Olga; Velli, Marco

2016-05-01

The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop the specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers (PSs) if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of PSs shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at the PS base low in the corona.

Quantification of Processing Effects on Filament Wound Pressure Vessels

NASA Technical Reports Server (NTRS)

Aiello, Robert A.; Chamis, Christos C.

1999-01-01

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 C C! end cap shape. The finite element model generated is composed of plate type quadrilateral shell elements on the entire vessel surface. This computational procedure can also be sued to generate grid, connectivity and material cards (bulk data) for component parts of a larger model. These bulk data are assigned to a user designated file for finite element structural/stress analysis of composite pressure vessels. The procedure accommodates filament would pressure vessels of all types of shells-of-revolution. It has provisions to readily evaluate initial stresses due to pretension in the winding filaments and residual stresses due to cure temperature.

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The proposed TFM has a modular structure with quasi-U stator cores and toroidal ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating setup to achieve high air gap flux density. Pole number selection is critical in the design process of a TFM as it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the initial design procedure. The effect of pole shaping on back-EMF andmore » inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis (FEA). A proof-of-concept prototype was developed to experimentally validate the FEA results.« less

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

DOE PAGES

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz; ...

2018-03-12

This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The proposed TFM has a modular structure with quasi-U stator cores and toroidal ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating setup to achieve high air gap flux density. Pole number selection is critical in the design process of a TFM as it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the initial design procedure. The effect of pole shaping on back-EMF andmore » inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis (FEA). A proof-of-concept prototype was developed to experimentally validate the FEA results.« less

Electrical machines with superconducting windings. Part 3: Homopolar dc machines

NASA Astrophysics Data System (ADS)

Kullman, D.; Henninger, P.

1981-01-01

The losses in rotating liquid metal contacts and the problems in including liquid metals were theoretically and experimentally studied. These machines are shown realiable. For electric ship propulsion, they are a more efficient method of power transmission than mechanical gearboxes. However, weight reduction as compared to mechanical gearboxes can hardly be achieved with machines fully shielded by magnetic iron.

Wind machines. [aerodynamics of sailwing vehicles

NASA Technical Reports Server (NTRS)

Lissaman, P. B. S.

1973-01-01

The basic elements of the air/water momentum exchange are described by the environment, the potential, the air and water subsystems, the total system, and the rule. Many of these topics have direct analogues in aerogenerator design. Aspects of optimal sail design and of waveless hulls are briefly outlined. A wind driven vehicle capable of moving directly downwind faster than the wind, is reported. The lecture is illustrated with slides and movie clips showing surfing catamarans, land and water versions of the Bauer vehicle, hang gliding, land sailing, and wind surfing.

Filament Channel Formation, Eruption, and Jet Generation

NASA Astrophysics Data System (ADS)

DeVore, C. Richard; Antiochos, Spiro K.; Karpen, Judith T.

2017-08-01

The mechanism behind filament-channel formation is a longstanding mystery, while that underlying the initiation of coronal mass ejections and jets has been studied intensively but is not yet firmly established. In previous work, we and collaborators have investigated separately the consequences of magnetic-helicity condensation (Antiochos 2013) for forming filament channels (Zhao et al. 2015; Knizhnik et al. 2015, 2017a,b) and of the embedded-bipole model (Antiochos 1996) for generating reconnection-driven jets (Pariat et al. 2009, 2010, 2015, 2016; Wyper et al. 2016, 2017). Now we have taken a first step toward synthesizing these two lines of investigation. Our recent study (Karpen et al. 2017) of coronal-hole jets with gravity and wind employed an ad hoc, large-scale shear flow at the surface to introduce magnetic free energy and form the filament channel. In this effort, we replace the shear flow with an ensemble of local rotation cells, to emulate the Sun’s ever-changing granules and supergranules. As in our previous studies, we find that reconnection between twisted flux tubes within the closed-field region concentrates magnetic shear and free energy near the polarity inversion line, forming the filament channel. Onset of reconnection between this field and the external, unsheared, open field releases stored energy to drive the impulsive jet. We discuss the results of our new simulations with implications for understanding solar activity and space weather.

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.

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.

Quantifying the impact of an upwelling filament on the physical-chemical-biological interactions off SW Iberia

NASA Astrophysics Data System (ADS)

Cravo, A.; Sanchez, R.; Monteiro, C.; Cardeira, S.; Madureira, M.; Rita, F.; Relvas, P.

2017-12-01

Upwelling filaments are mesoscale structures of cold water that stretch seaward in a tongue-like shape with origin in the coastal upwelling zone. Filaments off the Iberian Peninsula are recurrent, showing similarities with those in the Californian coast. The Cape São Vicente, the SW tip of the Iberian Peninsula, is the root of recurrent filaments observed in the satellite imagery during the upwelling season. However, the understanding of its physical and chemical impact on the biological productivity is rather limited. There, a relatively small filament ( 80 km long) was investigated through remote sensing and in situ multidisciplinary observations during an upwelling favourable wind relaxation event, but just after an intense upwelling period. A total of 42 CTD+Rosette casts up to 400 m depth were distributed on an almost regular grid of 15 km mean spacing guided by guided by satellite SST imagery transmitted to the ship in near-real time. The parameters sampled during the sea campaign included: velocity field sampled along the ship track through a hull-mounted 38 kHz RDI ADCP, meteorological variables, temperature, salinity, chlorophyll a, dissolved oxygen, nitrate, phosphate, silicate, cadmium, lead and zinc. The extent of the impact of the filament was evaluated by quantifying the cross-shelf transports of several properties. The amounts conveyed by the filament were much stronger than those expected by the wind-driven Ekman mechanism, showing that it represents an efficient feature for the exchange of water, dissolved and particulate matter from the productive shelf towards the oligotrophic offshore region. Considering the periods of strong upwelling events and the extent of their duration along the year, the amounts of exported matter will certainly enhance the biological productivity of these waters, including its fisheries. These filament data contribute to better understand the physical-chemical-biological interactions of this regional ecosystem.

Wind Power Now!

ERIC Educational Resources Information Center

Inglis, David Rittenhouse

1975-01-01

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

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.

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic andmore » changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.« less

Axial gap rotating electrical machine

DOEpatents

None

2016-02-23

Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.

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.

Mutation-specific effects on thin filament length in thin filament myopathy.

PubMed

Winter, Josine M de; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A; Pappas, Christopher T; Gregorio, Carol C; Stienen, Ger J M; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B; Engelen, Baziel G van; Voermans, Nicol C; Donkervoort, Sandra; Bönnemann, C G; Clarke, Nigel F; Beggs, Alan H; Granzier, Henk; Ottenheijm, Coen A C

2016-06-01

Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation. We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force-sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin-thick filament overlap. These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. Ann Neurol 2016;79:959-969. © 2016 American Neurological Association.

Mutation-Specific Effects on Thin Filament Length in Thin Filament Myopathy

PubMed Central

de Winter, Josine M.; Joureau, Barbara; Lee, Eun-Jeong; Kiss, Balázs; Yuen, Michaela; Gupta, Vandana A.; Pappas, Christopher T.; Gregorio, Carol C.; Stienen, Ger J. M.; Edvardson, Simon; Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Pelin, Katarina; Malfatti, Edoardo; Romero, Norma B.; van Engelen, Baziel G.; Voermans, Nicol C.; Donkervoort, Sandra; Bönnemann, C. G.; Clarke, Nigel F.; Beggs, Alan H.; Granzier, Henk; Ottenheijm, Coen A. C.

2016-01-01

Objective Thin filament myopathies are among the most common nondystrophic congenital muscular disorders, and are caused by mutations in genes encoding proteins that are associated with the skeletal muscle thin filament. Mechanisms underlying muscle weakness are poorly understood, but might involve the length of the thin filament, an important determinant of force generation. Methods We investigated the sarcomere length-dependence of force, a functional assay that provides insights into the contractile strength of muscle fibers as well as the length of the thin filaments, in muscle fibers from 51 patients with thin filament myopathy caused by mutations in NEB, ACTA1, TPM2, TPM3, TNNT1, KBTBD13, KLHL40, and KLHL41. Results Lower force generation was observed in muscle fibers from patients of all genotypes. In a subset of patients who harbor mutations in NEB and ACTA1, the lower force was associated with downward shifted force–sarcomere length relations, indicative of shorter thin filaments. Confocal microscopy confirmed shorter thin filaments in muscle fibers of these patients. A conditional Neb knockout mouse model, which recapitulates thin filament myopathy, revealed a compensatory mechanism; the lower force generation that was associated with shorter thin filaments was compensated for by increasing the number of sarcomeres in series. This allowed muscle fibers to operate at a shorter sarcomere length and maintain optimal thin–thick filament overlap. Interpretation These findings might provide a novel direction for the development of therapeutic strategies for thin filament myopathy patients with shortened thin filament lengths. PMID:27074222

Diagnosis of femtosecond plasma filament by channeling microwaves along the filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alshershby, Mostafa; Ren, Yu; Qin, Jiang

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.

Is titin a ‘winding filament’? A new twist on muscle contraction

PubMed Central

Nishikawa, Kiisa C.; Monroy, Jenna A.; Uyeno, Theodore E.; Yeo, Sang Hoon; Pai, Dinesh K.; Lindstedt, Stan L.

2012-01-01

Recent studies have demonstrated a role for the elastic protein titin in active muscle, but the mechanisms by which titin plays this role remain to be elucidated. In active muscle, Ca2+-binding has been shown to increase titin stiffness, but the observed increase is too small to explain the increased stiffness of parallel elastic elements upon muscle activation. We propose a ‘winding filament’ mechanism for titin's role in active muscle. First, we hypothesize that Ca2+-dependent binding of titin's N2A region to thin filaments increases titin stiffness by preventing low-force straightening of proximal immunoglobulin domains that occurs during passive stretch. This mechanism explains the difference in length dependence of force between skeletal myofibrils and cardiac myocytes. Second, we hypothesize that cross-bridges serve not only as motors that pull thin filaments towards the M-line, but also as rotors that wind titin on the thin filaments, storing elastic potential energy in PEVK during force development and active stretch. Energy stored during force development can be recovered during active shortening. The winding filament hypothesis accounts for force enhancement during stretch and force depression during shortening, and provides testable predictions that will encourage new directions for research on mechanisms of muscle contraction. PMID:21900329

Classifying Structures in the ISM with Machine Learning Techniques

NASA Astrophysics Data System (ADS)

Beaumont, Christopher; Goodman, A. A.; Williams, J. P.

2011-01-01

The processes which govern molecular cloud evolution and star formation often sculpt structures in the ISM: filaments, pillars, shells, outflows, etc. Because of their morphological complexity, these objects are often identified manually. Manual classification has several disadvantages; the process is subjective, not easily reproducible, and does not scale well to handle increasingly large datasets. We have explored to what extent machine learning algorithms can be trained to autonomously identify specific morphological features in molecular cloud datasets. We show that the Support Vector Machine algorithm can successfully locate filaments and outflows blended with other emission structures. When the objects of interest are morphologically distinct from the surrounding emission, this autonomous classification achieves >90% accuracy. We have developed a set of IDL-based tools to apply this technique to other datasets.

PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan

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 Hα 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 extrapolationsmore » 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.« less

Large, low cost composite wind turbine blades

NASA Technical Reports Server (NTRS)

Gewehr, H. W.

1979-01-01

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

Design Considerations of a Transverse Flux Machine for Direct-Drive Wind Turbine Applications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic andmore » changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification.« less

Prediction of the far field noise from wind energy farms

NASA Technical Reports Server (NTRS)

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

1986-01-01

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

Wind Power Utilization Guide.

DTIC Science & Technology

1981-09-01

The expres- sions for the rotor torque for a Darrieus machine can be found in Reference 4.16. The Darrieus wind turbine offers the following... turbine generators, wind -driven turbines , power conditioning, wind power, energy conservation, windmills, economic ana \\sis. 20 ABS 1"ACT (Conti,on... turbines , power conditioning requirements, siting requirements, and the economics of wind power under different conditions. Three examples are given to

Hybrid-secondary uncluttered induction machine

DOEpatents

Hsu, John S.

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.

Lay-Up and Consolidation of a Composite Pipe by In Situ Ultrasonic Welding of a Thermoplastic Matrix Composite Tape.

PubMed

Dell'Anna, Riccardo; Lionetto, Francesca; Montagna, Francesco; Maffezzoli, Alfonso

2018-05-11

In this work, the potential of preformed thermoplastic matrix composite tapes for the manufacturing of composite pipes by filament winding assisted by in situ ultrasonic welding was evaluated. Unidirectional tapes of E-glass-reinforcedamorphous poly (ethylene terephthalate) were laid up and consolidated in a filament winding machine that was modified with a set-up enabling ultrasonic welding. The obtained composite specimens were characterized by means of morphological and dynamic mechanical analysis as well as void content evaluation, in order to correlate welding parameters to composite properties.

Damage Model and Progressive Failure Analyses for Filament Wound Composite Laminates

NASA Astrophysics Data System (ADS)

Ribeiro, Marcelo Leite; Vandepitte, Dirk; Tita, Volnei

2013-10-01

Recent improvements in manufacturing processes and materials properties associated with excellent mechanical characteristics and low weight have made composite materials very attractive for application on civil aircraft structures. However, even new designs are still very conservative, because the composite failure phenomenon is very complex. Several failure criteria and theories have been developed to describe the damage process and how it evolves, but the solution of the problem is still open. Moreover, modern filament winding techniques have been used to produce a wide variety of structural shapes not only cylindrical parts, but also “flat” laminates. Therefore, this work presents the development of a damage model and its application to simulate the progressive failure of flat composite laminates made using a filament winding process. The damage model was implemented as a UMAT (User Material Subroutine), in ABAQUSTM Finite Element (FE) framework. Progressive failure analyses were carried out using FE simulation in order to simulate the failure of flat filament wound composite structures under different loading conditions. In addition, experimental tests were performed in order to identify parameters related to the material model, as well as to evaluate both the potential and the limitations of the model. The difference between numerical and the average experimental results in a four point bending set-up is only 1.6 % at maximum load amplitude. Another important issue is that the model parameters are not so complicated to be identified. This characteristic makes this model very attractive to be applied in an industrial environment.

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,…

Cogging Torque Minimization in Transverse Flux Machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Hasan, Iftekhar; Sozer, Yilmaz

2017-02-16

This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOE) based on the Taguchi method.more » A three-level DOE is performed to reach an optimum solution with minimum simulations. Finite element analysis is used to study the different effects. Two prototypes are being fabricated for experimental verification.« less

Low cost composite materials for wind energy conversion systems

NASA Technical Reports Server (NTRS)

Weingart, O.

1980-01-01

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).

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.

Equivalent model of a dually-fed machine for electric drive control systems

NASA Astrophysics Data System (ADS)

Ostrovlyanchik, I. Yu; Popolzin, I. Yu

2018-05-01

The article shows that the mathematical model of a dually-fed machine is complicated because of the presence of a controlled voltage source in the rotor circuit. As a method of obtaining a mathematical model, the method of a generalized two-phase electric machine is applied and a rotating orthogonal coordinate system is chosen that is associated with the representing vector of a stator current. In the chosen coordinate system in the operator form the differential equations of electric equilibrium for the windings of the generalized machine (the Kirchhoff equation) are written together with the expression for the moment, which determines the electromechanical energy transformation in the machine. Equations are transformed so that they connect the currents of the windings, that determine the moment of the machine, and the voltages on these windings. The structural diagram of the machine is assigned to the written equations. Based on the written equations and accepted assumptions, expressions were obtained for the balancing the EMF of windings, and on the basis of these expressions an equivalent mathematical model of a dually-fed machine is proposed, convenient for use in electric drive control systems.

Lay-Up and Consolidation of a Composite Pipe by In Situ Ultrasonic Welding of a Thermoplastic Matrix Composite Tape

PubMed Central

Dell’Anna, Riccardo; Montagna, Francesco

2018-01-01

In this work, the potential of preformed thermoplastic matrix composite tapes for the manufacturing of composite pipes by filament winding assisted by in situ ultrasonic welding was evaluated. Unidirectional tapes of E-glass-reinforcedamorphous poly (ethylene terephthalate) were laid up and consolidated in a filament winding machine that was modified with a set-up enabling ultrasonic welding. The obtained composite specimens were characterized by means of morphological and dynamic mechanical analysis as well as void content evaluation, in order to correlate welding parameters to composite properties. PMID:29751693

Comparison of hand laid-up tape and filament wound composite cylinders and panels with and without impact damage

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Lopez, Osvaldo F.

1991-01-01

Experimentally determined axial compressive failure loads, strains and failure modes of composite flat panels and cylinders are presented. A comparison of two types of filament wound flat graphite-epoxy panels indicates that the winding pattern can influence structural response. A comparison of hand laid-up tape and filament wound composite cylinders indicates that fabrication method may not significantly influence the failure mode or average failure strain of thick-walled (radius-to-thickness ratio less than 15) graphite-epoxy cylinders. The interaction of manufacturing-induced features (fiber cross-overs) and low-speed impact damage for graphite-epoxy specimens is also presented. Filament would flat panels with many fiber cross-overs exhibited lower failure strains than filament wound panels without fiber cross-overs for all impact speeds examined. Graphite-thermoplastic cylinders exhibited a significantly different failure mode from the graphite-epoxy cylinders.

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.

Wind energy education projects. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziegler, P.; Conlon, T.R.; Arcadi, T.

Two projects under DOE's Small-Scale Appropriate Energy Technology Grants Program have educated the public in a hands on way about wind energy systems. The first was awarded to Peter Ziegler of Berkeley, California, to design and build a walk-through exhibition structure powered by an adjoining wind-generator. This Wind Energy Pavilion was erected at Fort Funston in the Golden Gate National Recreation Area. It currently serves both as an enclosure for batteries and a variety of monitoring instruments, and as a graphic environment where the public can learn about wind energy. The second project, entitled Wind and Kid Power, involved anmore » educational program for a classroom of first through third grades in the Vallejo, Unified School District. The students studied weather, measured wind speeds and built small models of wind machines. They also built a weather station, and learned to use weather instruments. The grant funds enabled them to actually build and erect a Savonius wind machine at the Loma Vista Farm School.« less

The Formation of Filamentary Structures in Radiative Cluster Winds

NASA Astrophysics Data System (ADS)

Rodríguez-González, Ary; Esquivel, Alejandro; Raga, Alejandro C.; Cantó, Jorge

We explore the dynamics of a "cluster wind" flow in the regime in which the shocks resulting from the interaction of winds from nearby stars are radiative. We show that for a cluster with low-intermedia mass stars, the wind interactions are indeed likely to be radiative. We then compute three dimensional, radiative simulations of a cluster of 75 young stars, exploring the effects of varying the wind parameters and the density of the initial ISM that permeates the volume of the cluster. These simulations show that the ISM is compressed by the action of the winds into a structure of dense knots and filaments.

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

NASA Technical Reports Server (NTRS)

Erdogan, F.; Pacella, A. H.

1973-01-01

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

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.

Cape Blanco wind farm feasibility study

NASA Astrophysics Data System (ADS)

1987-11-01

The Cape Blanco Wind Farm (CBWF) Feasibility Study was undertaken as a prototype for determining the feasibility of proposals for wind energy projects at Northwest sites. It was intended to test for conditions under which wind generation of electricity could be commercially feasible, not by another abstract survey of alternative technologies, but rather through a site-specific, machine-specific analysis of one proposal. Some of the study findings would be most pertinent to the Cape Blanco site - local problems require local solutions. Other findings would be readily applicable to other sites and other machines, and study methodologies would be designed to be modified for appraisal of other proposals. This volume discusses environmental, economic, and technical issues of the Wind Farm.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José

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 frommore » 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.« less

Development of large, horizontal-axis wind turbines

NASA Technical Reports Server (NTRS)

Baldwin, D. H.; Kennard, J.

1985-01-01

A program to develop large, horizontal-axis wind turbines is discussed. The program is directed toward developing the technology for safe, reliable, environmentally acceptable large wind turbines that can generate a significant amount of electricity at costs competitive with those of conventional electricity-generating systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Several ongoing projects in large-wind-turbine development are directed toward meeting the technology requirements for utility applications. The machines based on first-generation technology (Mod-OA and Mod-1) successfully completed their planned periods of experimental operation in June, 1982. The second-generation machines (Mod-2) are in operation at selected utility sites. A third-generation machine (Mod-5) is under contract. Erection and initial operation of the Mod-5 in Hawaii should take place in 1986. Each successive generation of technology increased reliability and energy capture while reducing the cost of electricity. These advances are being made by gaining a better understanding of the system-design drivers, improving the analytical design tools, verifying design methods with operating field data, and incorporating new technology and innovative designs. Information is given on the results from the first- and second-generation machines (Mod-OA, - 1, and -2), the status of the Department of Interior, and the status of the third-generation wind turbine (Mod-5).

Twisted ribbon structure of paired helical filaments revealed by atomic force microscopy.

PubMed

Pollanen, M S; Markiewicz, P; Bergeron, C; Goh, M C

1994-05-01

Progressive deposition of phosphorylated tau into the paired helical filaments (PHF) that compose neurofibrillary tangles, dystrophic neurites, and neuropil threads is an obligate feature of Alzheimer's disease. The standard model of PHF structure, derived from electron microscopic studies, suggests that two 8- to 10-nm filaments each composed of three to four protofilaments are wound into a helix with a maximal diameter of -20 nm and a half period of 65 to 80 nm. However, recent vertical platinum-carbon replicas of PHF more closely resemble a thin helical ribbon without constitutive protofilaments. Here we report that native PHF imaged with an atomic force microscope appear as twisted ribbons rather than the generally accepted structure derived from electron microscopic studies. These data imply that the assembly of PHF is not due to the twisting of pair-wise filaments but rather the helical winding of self-associated tau molecules arranged into a flattened structure. Future structural models of PHF should be based on quantitative data obtained from imaging techniques, such as scanning probe microscopy, which do not require harsh specimen preparation procedures.

Spontaneous Wave Generation from Submesoscale Fronts and Filaments

NASA Astrophysics Data System (ADS)

Shakespeare, C. J.; Hogg, A.

2016-02-01

Submesoscale features such as eddies, fronts, jets and filaments can be significant sources of spontaneous wave generation at the ocean surface. Unlike near-inertial waves forced by winds, these spontaneous waves are typically of higher frequency and can propagate through the thermocline, whereupon they break and drive mixing in the ocean interior. Here we investigate the spontaneous generation, propagation and subsequent breaking of these waves using a combination of theory and submesoscale resolving numerical models. The mechanism of generation is nearly identical to that of lee waves where flow is deflected over a rigid obstacle on the sea floor. Here, very sharp fronts and filaments of order 100m width moving in the submesoscale surface flow generate "surface lee waves" by presenting an obstacle to the surrounding stratified fluid. Using our numerical model we quantify the net downward wave energy flux from the surface, and where it is dissipated in the water column. Our results suggest an alternative to the classical paradigm where the energy associated with mixing in the ocean interior is sourced from bottom-generated lee waves.

The Solar Wind from Pseudostreamers and their Environs: Opportunities for Observations with Parker Solar Probe and Solar Orbiter

NASA Astrophysics Data System (ADS)

Panasenco, O.; Velli, M.; Panasenco, A.; Lionello, R.

2017-12-01

The solar dynamo and photospheric convection lead to three main types of structures extending from the solar surface into the corona - active regions, solar filaments (prominences when observed at the limb) and coronal holes. These structures exist over a wide range of scales, and are interlinked with each other in evolution and dynamics. Active regions can form clusters of magnetic activity and the strongest overlie sunspots. In the decay of active regions, the boundaries separating opposite magnetic polarities (neutral lines) develop specific structures called filament channels above which filaments form. In the presence of flux imbalance decaying active regions can also give birth to lower latitude coronal holes. The accumulation of magnetic flux at coronal hole boundaries also creates conditions for filament formation: polar crown filaments are permanently present at the boundaries of the polar coronal holes. Mid-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers if other coronal holes of the same polarity are present. While helmet streamers form between open fields of opposite polarities, the pseudostreamer, characterized by a smaller coronal imprint, typically shows a more prominent straight ray or stalk extending from the corona. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. Here we discuss the specific role of filament channels on pseudostreamer topology and on solar wind properties. 1D numerical analysis of pseudostreamers shows that the properties of the solar wind from around PSs depend on the presence/absence of filament channels, number of channels and chirality at thepseudostreamer base low in the corona. We review and model possible coronal magnetic configurations and solar wind plasma properties at different distances from the solar surface that

Sliding movement of single actin filaments on one-headed myosin filaments

NASA Astrophysics Data System (ADS)

Harada, Yoshie; Noguchi, Akira; Kishino, Akiyoshi; Yanagida, Toshio

1987-04-01

The myosin molecule consists of two heads, each of which contains an enzymatic active site and an actin-binding site. The fundamental problem of whether the two heads function independently or cooperatively during muscle contraction has been studied by methods using an actomyosin thread1, superprecipitation2-4 and chemical modification of muscle fibres5. No clear conclusion has yet been reached. We have approached this question using an assay system in which sliding movements of fluorescently labelled single actin filaments along myosin filaments can be observed directly6,7. Here, we report direct measurement of the sliding of single actin filaments along one-headed myosin filaments in which the density of heads was varied over a wide range. Our results show that cooperative interaction between the two heads of myosin is not essential for inducing the sliding movement of actin filaments.

Transition of Femtosecond-Filament-Solid Interactions from Single to Multiple Filament Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skrodzki, P. J.; Burger, M.; Jovanovic, I.

High-peak-power fs-laser filaments offer unique characteristics attractive to remote sensing via techniques such as remote laser-induced breakdown spectroscopy (R-LIBS). The dynamics of several ablation mechanisms following the interaction between a filament and a solid determines the emission strength and reproducibility of target plasma, which is of relevance for R-LIBS applications. Here, we investigate the space- and time-resolved dynamics of ionic and atomic emission from copper as well as the surrounding atmosphere in order to understand limitations of fs-filament-ablation for standoff energy delivery. Furthermore, we probe the shock front produced from filament-target interaction using time-resolved shadowgraphy and infer laser-material coupling efficienciesmore » for both single and multiple filament regimes through analysis of shock expansion with the Sedov model for point detonation. The results provide insight into plasma structure for the range of peak powers up to 30 times the critical power for filamentation P cr. Despite the stochastic nucleation of multiple filaments at peak-powers greater than 16 P cr, emission of ionic and neutral species increases with pump beam intensity, and short-lived nitrogen emission originating from the ambient is consistently observed. Ultimately, results suggest favorable scaling of emission intensity from target species on the laser pump energy, furthering the prospects for use of filament-solid interactions for remote sensing.« less

Transition of Femtosecond-Filament-Solid Interactions from Single to Multiple Filament Regime

DOE PAGES

Skrodzki, P. J.; Burger, M.; Jovanovic, I.

2017-10-06

High-peak-power fs-laser filaments offer unique characteristics attractive to remote sensing via techniques such as remote laser-induced breakdown spectroscopy (R-LIBS). The dynamics of several ablation mechanisms following the interaction between a filament and a solid determines the emission strength and reproducibility of target plasma, which is of relevance for R-LIBS applications. Here, we investigate the space- and time-resolved dynamics of ionic and atomic emission from copper as well as the surrounding atmosphere in order to understand limitations of fs-filament-ablation for standoff energy delivery. Furthermore, we probe the shock front produced from filament-target interaction using time-resolved shadowgraphy and infer laser-material coupling efficienciesmore » for both single and multiple filament regimes through analysis of shock expansion with the Sedov model for point detonation. The results provide insight into plasma structure for the range of peak powers up to 30 times the critical power for filamentation P cr. Despite the stochastic nucleation of multiple filaments at peak-powers greater than 16 P cr, emission of ionic and neutral species increases with pump beam intensity, and short-lived nitrogen emission originating from the ambient is consistently observed. Ultimately, results suggest favorable scaling of emission intensity from target species on the laser pump energy, furthering the prospects for use of filament-solid interactions for remote sensing.« less

Operational results for the experimental DOE/NASA Mod-OA wind turbine project

NASA Astrophysics Data System (ADS)

Shaltens, R. K.; Birchenough, A. G.

The Mod-OA wind turbine project which was to gain early experience in the operation of large wind turbines in a utility environment is discussed. The Mod-OA wind turbines were a first generation design, and even though not cost effective, the operating experience and performance characteristics had a significant effect on the design and development of the second and third generation machines. The Mod-OA machines were modified as a result of the operational experience, particularly the blade development and control system strategy. The results of study to investigate the interaction of a Mod-OA wind turbine with an isolated diesel generation system are discussed. The machine configuration, its advantages and disadvantages and the machine performance and availability are discussed.

Operational results for the experimental DOE/NASA Mod-OA wind turbine project

NASA Technical Reports Server (NTRS)

Shaltens, R. K.; Birchenough, A. G.

1983-01-01

The Mod-OA wind turbine project which was to gain early experience in the operation of large wind turbines in a utility environment is discussed. The Mod-OA wind turbines were a first generation design, and even though not cost effective, the operating experience and performance characteristics had a significant effect on the design and development of the second and third generation machines. The Mod-OA machines were modified as a result of the operational experience, particularly the blade development and control system strategy. The results of study to investigate the interaction of a Mod-OA wind turbine with an isolated diesel generation system are discussed. The machine configuration, its advantages and disadvantages and the machine performance and availability are discussed.

Possibilities and limitations of wind energy utilisation

NASA Astrophysics Data System (ADS)

Feustel, J.

1981-10-01

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

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…

Apparatus for cooling an electric machine

DOEpatents

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

2013-07-16

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

Galactic cold cores. VIII. Filament formation and evolution: Filament properties in context with evolutionary models

NASA Astrophysics Data System (ADS)

Rivera-Ingraham, A.; Ristorcelli, I.; Juvela, M.; Montillaud, J.; Men'shchikov, A.; Malinen, J.; Pelkonen, V.-M.; Marston, A.; Martin, P. G.; Pagani, L.; Paladini, R.; Paradis, D.; Ysard, N.; Ward-Thompson, D.; Bernard, J.-P.; Marshall, D. J.; Montier, L.; Tóth, L. V.

2017-05-01

Context. The onset of star formation is intimately linked with the presence of massive unstable filamentary structures. These filaments are therefore key for theoretical models that aim to reproduce the observed characteristics of the star formation process in the Galaxy. Aims: As part of the filament study carried out by the Herschel Galactic Cold Cores Key Programme, here we study and discuss the filament properties presented in GCC VII (Paper I) in context with theoretical models of filament formation and evolution. Methods: A conservatively selected sample of filaments located at a distance D< 500 pc was extracted from the GCC fields with the getfilaments algorithm. The physical structure of the filaments was quantified according to two main components: the central (Gaussian) region of the filament (core component), and the power-law-like region dominating the filament column density profile at larger radii (wing component). The properties and behaviour of these components relative to the total linear mass density of the filament and the column density of its environment were compared with the predictions from theoretical models describing the evolution of filaments under gravity-dominated conditions. Results: The feasibility of a transition from a subcritical to supercritical state by accretion at any given time is dependent on the combined effect of filament intrinsic properties and environmental conditions. Reasonably self-gravitating (high Mline,core) filaments in dense environments (AV≳ 3 mag) can become supercritical on timescales of t 1 Myr by accreting mass at constant or decreasing width. The trend of increasing Mline,tot (Mline,core and Mline,wing) and ridge AV with background for the filament population also indicates that the precursors of star-forming filaments evolve coevally with their environment. The simultaneous increase of environment and filament AV explains the observed association between dense environments and high Mline,core values

DOE/NASA Mod-0 100KW wind turbine test results

NASA Technical Reports Server (NTRS)

Glasgow, J. C.

1978-01-01

The Wind Turbine demonstrates the capability of automatic unattended operation, including startup, achieving synchronism, and shutdown as dictated by wind conditions. During the course of these operations, a wealth of engineering data was generated. Some of the data which is associated with rotor and machine dynamics problems encountered, and the machine modifications incorporated as a solution are presented. These include high blade loads due to tower shadow, excessive nacelle yawing motion, and power oscillations. The results of efforts to correlate measured wind velocity with power output and wind turbine loads are also discussed.

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.

System for maintaining the alignment of mandrels in filament winding operations

DOEpatents

Robinson, Samuel C.; Dodge, William G.; Pollard, Roy E.

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.

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

Twisted ribbon structure of paired helical filaments revealed by atomic force microscopy.

PubMed Central

Pollanen, M. S.; Markiewicz, P.; Bergeron, C.; Goh, M. C.

1994-01-01

Progressive deposition of phosphorylated tau into the paired helical filaments (PHF) that compose neurofibrillary tangles, dystrophic neurites, and neuropil threads is an obligate feature of Alzheimer's disease. The standard model of PHF structure, derived from electron microscopic studies, suggests that two 8- to 10-nm filaments each composed of three to four protofilaments are wound into a helix with a maximal diameter of -20 nm and a half period of 65 to 80 nm. However, recent vertical platinum-carbon replicas of PHF more closely resemble a thin helical ribbon without constitutive protofilaments. Here we report that native PHF imaged with an atomic force microscope appear as twisted ribbons rather than the generally accepted structure derived from electron microscopic studies. These data imply that the assembly of PHF is not due to the twisting of pair-wise filaments but rather the helical winding of self-associated tau molecules arranged into a flattened structure. Future structural models of PHF should be based on quantitative data obtained from imaging techniques, such as scanning probe microscopy, which do not require harsh specimen preparation procedures. Images Figure 1 PMID:8178938

Variabilities detected by acoustic emission from filament-wound Aramid fiber/epoxy composite pressure vessels

NASA Technical Reports Server (NTRS)

Hamstad, M. A.

1978-01-01

Two hundred and fifty Aramid fiber/epoxy pressure vessels were filament-wound over spherical aluminum mandrels under controlled conditions typical for advanced filament-winding. A random set of 30 vessels was proof-tested to 74% of the expected burst pressure; acoustic emission data were obtained during the proof test. A specially designed fixture was used to permit in situ calibration of the acoustic emission system for each vessel by the fracture of a 4-mm length of pencil lead (0.3 mm in diameter) which was in contact with the vessel. Acoustic emission signatures obtained during testing showed larger than expected variabilities in the mechanical damage done during the proof tests. To date, identification of the cause of these variabilities has not been determined.

Cytoplasmic filaments of Amoeba proteus. I. The role of filaments in consistency changes and movement.

PubMed

Pollard, T D; Ito, S

1970-08-01

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 degrees 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 degrees 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.

Hybrid Wound Filaments for Greater Resistance to Impacts

NASA Technical Reports Server (NTRS)

DeLay, Thomas K.; Patterson, James E.; Olson, Michael A.

2008-01-01

A hybrid material containing wound filaments made of a hybrid of high-strength carbon fibers and poly(phenylene benzobisoxazole) [PBO] fibers is discussed. This hybrid material is chosen in an effort to increase the ability of the pressure vessel to resist damage by low-speed impacts (e.g., dropping of tools on the vessel or bumping of the vessel against hard objects during installation and use) without significantly increasing the weight of the vessel. While the basic concept of hybridizing fibers in filament-wound structures is not new, the use of hybridization to increase resistance to impacts is an innovation, and can be expected to be of interest in the composite-pressure-vessel industry. The precise types and the proportions of the high-strength carbon fibers and the PBO fibers in the hybrid are chosen, along with the filament-winding pattern, to maximize the advantageous effects and minimize the disadvantageous effects of each material. In particular, one seeks to (1) take advantage of the ability of the carbon fibers to resist stress rupture while minimizing their contribution to vulnerability of the vessel to impact damage and (2) take advantage of the toughness of the PBO fibers while minimizing their contribution to vulnerability of the vessel to stress rupture. Experiments on prototype vessels fabricated according to this concept have shown promising results. At the time of reporting the information for this article, research toward understanding and optimizing the performances of PBO fibers so as to minimize their contribution to vulnerability of the pressure vessel to stress rupture had yet to be performed.

Solid friction between soft filaments.

PubMed

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.

PROPER MOTIONS AND BRIGHTNESS VARIATIONS OF NONTHERMAL X-RAY FILAMENTS IN THE CASSIOPEIA A SUPERNOVA REMNANT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patnaude, Daniel J.; Fesen, Robert A.

2009-05-20

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{sup -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 {rho}{sub ej} {proportional_to} r {sup -(7-9)} ejecta profile running into a circumstellarmore » 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 {approx} 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.« less

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

PubMed Central

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

2015-01-01

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

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

PubMed

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

2015-01-13

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

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.

The Geography of Wind Energy: Problem Solving Activities.

ERIC Educational Resources Information Center

Lahart, David E.; Allen, Rodney F.

1985-01-01

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

Wind Fins: Novel Lower-Cost Wind Power System

DOE Office of Scientific and Technical Information (OSTI.GOV)

David C. Morris; Dr. Will D. Swearingen

This project evaluated the technical feasibility of converting energy from the wind with a novel “wind fin” approach. This patent-pending technology has three major components: (1) a mast, (2) a vertical, hinged wind structure or fin, and (3) a power takeoff system. The wing structure responds to the wind with an oscillating motion, generating power. The overall project goal was to determine the basic technical feasibility of the wind fin technology. Specific objectives were the following: (1) to determine the wind energy-conversion performance of the wind fin and the degree to which its performance could be enhanced through basic designmore » improvements; (2) to determine how best to design the wind fin system to survive extreme winds; (3) to determine the cost-effectiveness of the best wind fin designs compared to state-of-the-art wind turbines; and (4) to develop conclusions about the overall technical feasibility of the wind fin system. Project work involved extensive computer modeling, wind-tunnel testing with small models, and testing of bench-scale models in a wind tunnel and outdoors in the wind. This project determined that the wind fin approach is technically feasible and likely to be commercially viable. Project results suggest that this new technology has the potential to harvest wind energy at approximately half the system cost of wind turbines in the 10kW range. Overall, the project demonstrated that the wind fin technology has the potential to increase the economic viability of small wind-power generation. In addition, it has the potential to eliminate lethality to birds and bats, overcome public objections to the aesthetics of wind-power machines, and significantly expand wind-power’s contribution to the national energy supply.« less

Wind utilization in remote regions: An economic study. [for comparison with diesel engines

NASA Technical Reports Server (NTRS)

Vansant, J. H.

1973-01-01

A wind driven generator was considered as a supplement to a diesel group, for the purpose of economizing fuel when wind power is available. A specific location on Hudson's Bay, Povognituk, was selected. Technical and economic data available for a wind machine of 10-kilowatt nominal capacity and available wind data for that region were used for the study. After subtracting the yearly wind machine costs from savings in fuel costs, a net savings of $1400 per year is realized. These values are approximate, but are though to be highly conservative.

Wind energy conversion system

DOEpatents

Longrigg, Paul

1987-01-01

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

Actin filament curvature biases branching direction

NASA Astrophysics Data System (ADS)

Wang, Evan; Risca, Viviana; Chaudhuri, Ovijit; Chia, Jia-Jun; Geissler, Phillip; Fletcher, Daniel

2012-02-01

Actin filaments are key components of the cellular machinery, vital for a wide range of processes ranging from cell motility to endocytosis. Actin filaments can branch, and essential in this process is a protein complex known as the Arp2/3 complex, which nucleate new ``daughter'' filaments from pre-existing ``mother'' filaments by attaching itself to the mother filament. Though much progress has been made in understanding the Arp2/3-actin junction, some very interesting questions remain. In particular, F-actin is a dynamic polymer that undergoes a wide range of fluctuations. Prior studies of the Arp2/3-actin junction provides a very static notion of Arp2/3 binding. The question we ask is how differently does the Arp2/3 complex interact with a straight filament compared to a bent filament? In this study, we used Monte Carlo simulations of a surface-tethered worm-like chain to explore possible mechanisms underlying the experimental observation that there exists preferential branch formation by the Arp2/3 complex on the convex face of a curved filament. We show that a fluctuation gating model in which Arp2/3 binding to the actin filament is dependent upon a rare high-local-curvature shape fluctuation of the filament is consistent with the experimental data.

SYMPATHETIC SOLAR FILAMENT ERUPTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Rui; Liu, Ying D.; Zimovets, Ivan

2016-08-10

The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filamentmore » that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.« less

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.

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

NASA Astrophysics Data System (ADS)

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

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.

Artificial neural networks for AC losses prediction in superconducting round filaments

NASA Astrophysics Data System (ADS)

Leclerc, J.; Makong Hell, L.; Lorin, C.; Masson, P. J.

2016-06-01

An extensive and fast method to estimate superconducting AC losses within a superconducting round filament carrying an AC current and subjected to an elliptical magnetic field (both rotating and oscillating) is presented. Elliptical fields are present in rotating machine stators and being able to accurately predict AC losses in fully superconducting machines is paramount to generating realistic machine designs. The proposed method relies on an analytical scaling law (ASL) combined with two artificial neural network (ANN) estimators taking 9 input parameters representing the superconductor, external field and transport current characteristics. The ANNs are trained with data generated by finite element (FE) computations with a commercial software (FlexPDE) based on the widely accepted H-formulation. After completion, the model is validated through comparison with additional randomly chosen data points and compared for simple field configurations to other predictive models. The loss estimation discrepancy is about 3% on average compared to the FEA analysis. The main advantages of the model compared to FE simulations is the fast computation time (few milliseconds) which allows it to be used in iterated design processes of fully superconducting machines. In addition, the proposed model provides a higher level of fidelity than the scaling laws existing in literature usually only considering pure AC field.

The Fluid Foil: The Seventh Simple Machine

ERIC Educational Resources Information Center

Mitts, Charles R.

2012-01-01

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

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

NASA Technical Reports Server (NTRS)

Erdogan, F.; Pacella, A. H.

1974-01-01

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

Tungsten Filament Fire

ERIC Educational Resources Information Center

Ruiz, Michael J.; Perkins, James

2016-01-01

We safely remove the outer glass bulb from an incandescent lamp and burn up the tungsten filament after the glass is removed. This demonstration dramatically illustrates the necessity of a vacuum or inert gas for the environment surrounding the tungsten filament inside the bulb. Our approach has added historical importance since the incandescent…

Rotating electric machine with fluid supported parts

DOEpatents

Smith, Jr., Joseph L.; Kirtley, Jr., James L.

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.

Electron emitting filaments for electron discharge devices

DOEpatents

Leung, Ka-Ngo; Pincosy, Philip A.; Ehlers, Kenneth W.

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.

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.

A solid-state controller for a wind-driven slip-ring induction generator

NASA Astrophysics Data System (ADS)

Velayudhan, C.; Bundell, J. H.; Leary, B. G.

1984-08-01

The three-phase induction generator appears to become the preferred choice for wind-powered systems operated in parallel with existing power systems. A problem arises in connection with the useful operating speed range of the squirrel-cage machine, which is relatively narrow, as, for instance, in the range from 1 to 1.15. Efficient extraction of energy from a wind turbine, on the other hand, requires a speed range, perhaps as large as 1 to 3. One approach for 'matching' the generator to the turbine for the extraction of maximum power at any usable wind speed involves the use of a slip-ring induction machine. The power demand of the slip-ring machine can be matched to the available output from the wind turbine by modifying the speed-torque characteristics of the generator. A description is presented of a simple electronic rotor resistance controller which can optimize the power taken from a wind turbine over the full speed range.

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…

Unwinding motion of a twisted active region filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, X. L.; Xue, Z. K.; Kong, D. F.

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,more » we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π 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.« less

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-12-30

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

Fabrication of Polylactide Nanocomposite Filament Using Melt Extrusion and Filament Characterization for 3D Printing

NASA Astrophysics Data System (ADS)

Jain, Shrenik Kumar

Fused deposition modeling (FDM) technology uses thermoplastic filament for layer by layer fabrication of objects. To make functional objects with desired properties, composite filaments are required in the FDM. In this thesis, less expensive mesoporous Nano carbon (NC) and carbon nanotube (CNT) infused in Polylactide (PLA) thermoplastic filaments were fabricated to improve the electrical properties and maintain sufficient strength for 3D printing. Solution blending was used for nanocomposite fabrication and melt extrusion was employed to make cylindrical filaments. Mechanical and electrical properties of 1 to 20 wt% of NC and 1 to 3 wt% of CNT filaments were investigated and significant improvement of conductivity (3.76 S/m) and sufficient yield strength (35MPa) were obtained. Scanning electron microscopy (SEM) images exhibited uniform dispersion of nanoparticles in polymer matrix and differential scanning calorimetry (DSC) results showed no significant changes in the glass transition temperature (Tg) for all the compositions. Perspective uses of this filament are for fabrication of electrical wires in 3D printed robots, drones, prosthetics, orthotics and others.

The Kinetics Underlying the Velocity of Smooth Muscle Myosin Filament Sliding on Actin Filaments in Vitro*

PubMed Central

Haldeman, Brian D.; Brizendine, Richard K.; Facemyer, Kevin C.; Baker, Josh E.; Cremo, Christine R.

2014-01-01

Actin-myosin interactions are well studied using soluble myosin fragments, but little is known about effects of myosin filament structure on mechanochemistry. We stabilized unphosphorylated smooth muscle myosin (SMM) and phosphorylated smooth muscle myosin (pSMM) filaments against ATP-induced depolymerization using a cross-linker and attached fluorescent rhodamine (XL-Rh-SMM). Electron micrographs showed that these side polar filaments are very similar to unmodified filaments. They are ∼0.63 μm long and contain ∼176 molecules. Rate constants for ATP-induced dissociation and ADP release from acto-myosin for filaments and S1 heads were similar. Actin-activated ATPases of SMM and XL-Rh-SMM were similarly regulated. XL-Rh-pSMM filaments moved processively on F-actin that was bound to a PEG brush surface. ATP dependence of filament velocities was similar to that for solution ATPases at high [actin], suggesting that both processes are limited by the same kinetic step (weak to strong transition) and therefore are attachment-limited. This differs from actin sliding over myosin monomers, which is primarily detachment-limited. Fitting filament data to an attachment-limited model showed that approximately half of the heads are available to move the filament, consistent with a side polar structure. We suggest the low stiffness subfragment 2 (S2) domain remains unhindered during filament motion in our assay. Actin-bound negatively displaced heads will impart minimal drag force because of S2 buckling. Given the ADP release rate, the velocity, and the length of S2, these heads will detach from actin before slack is taken up into a backwardly displaced high stiffness position. This mechanism explains the lack of detachment-limited kinetics at physiological [ATP]. These findings address how nonlinear elasticity in assemblies of motors leads to efficient collective force generation. PMID:24907276

Unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions

PubMed Central

Xu, B. F.; Wang, T. G.; Yuan, Y.; Cao, J. F.

2015-01-01

A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional rotational effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip. PMID:25583859

Novel Transverse Flux Machine for Vehicle Traction Applications: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Z.; Ahmed, A.; Husain, I.

2015-04-02

A novel transverse flux machine topology for electric vehicle traction applications using ferrite magnets is presented in this paper. The proposed transverse flux topology utilizes novel magnet arrangements in the rotor that are similar to the Halbach array to boost flux linkage; on the stator side, cores are alternately arranged around a pair of ring windings in each phase to make use of the entire rotor flux that eliminates end windings. Analytical design considerations and finite-element methods are used for an optimized design of a scooter in-wheel motor. Simulation results from finite element analysis (FEA) show that the motor achievedmore » comparable torque density to conventional rare-earth permanent magnet (PM) machines. This machine is a viable candidate for direct-drive applications with low cost and high torque density.« less

A Novel Transverse Flux Machine for Vehicle Traction Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, Zhao; Ahmed, Adeeb; Husain, Iqbal

2015-10-05

A novel transverse flux machine topology for electric vehicle traction application using ferrite magnets is presented in this paper. The proposed transverse flux topology utilizes novel magnet arrangements in the rotor that are similar to Halbach-array to boost flux linkage; on the stator side, cores are alternately arranged around a pair of ring windings in each phase to make use of the entire rotor flux that eliminates end windings. Analytical design considerations and finite element methods are used for an optimized design of a scooter in-wheel motor. Simulation results from Finite Element Analysis (FEA) show the motor achieved comparable torquemore » density to conventional rare-earth permanent magnet machines. This machine is a viable candidate for direct drive applications with low cost and high torque density.« less

Utility operational experience on the NASA/DOE MOD-0A 200-kW wind turbine

NASA Technical Reports Server (NTRS)

Glasgow, J. C.; Robbins, W. H.

1979-01-01

The Mod-0A 200 wind turbine was designed and fabricated as part of the Federal Wind Energy Program. Early wind turbine operation and performance data were obtained while gaining initial experience in the operation of large, horizontal axis wind turbines in typical utility environments. The Mod-0A wind turbine was turned over to the Town of Clayton Light and Water Plant, Clayton, NM, for utility operation and on December 31, 1978, the machine had completed ten months of utility operation. The machine is described and the recent operational experience at Clayton, NMis documented.

The Refined Shock Velocity of the X-Ray Filaments in the RCW 86 Northeast Rim

NASA Technical Reports Server (NTRS)

Yamaguchi, Hiroya; Katsuda, Satoru; Castro, Daniel; Williams, Brian J.; Lopez, Laura A.; Slane, Patrick O.; Smith, Randall K.; Petre, Robert

2017-01-01

A precise measurement of shock velocities is crucial for constraining the mechanism and efficiency of cosmic-ray (CR) acceleration at supernova remnant (SNR) shock fronts. The northeastern rim of the SNR RCW 86 is thought to be a particularly efficient CR acceleration site, owing to the recent result in which an extremely high shock velocity of 6000 km s1 was claimed. Here, we revisit the same SNR rim with the Chandra X-ray Observatory, 11 years after the first observation. This longer baseline than previously available allows us to determine a more accurate proper motion of the nonthermal X-ray filament, revealing a much lower velocity of 3000 340 km s1 (and even slower at a brighter region). Although the value has dropped to one-half of that from the previous X-ray measurement, it is still higher than the mean velocity of the H filaments in this region (1200 km s1). This discrepancy implies that the filaments bright in nonthermal X-rays and H emission trace different velocity components, and thus a CR pressure constrained by combining the X-ray kinematics and the H spectroscopy can easily be overestimated. We also measure the proper motion of the thermal X-ray filament immediately to the south of the nonthermal one. The inferred velocity (720 360 km s1) is significantly lower than that of the nonthermal filament, suggesting the presence of denser ambient material, possibly a wall formed by a wind from the progenitor, which has drastically slowed down the shock.

Implementing Machine Learning in the PCWG Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clifton, Andrew; Ding, Yu; Stuart, Peter

The Power Curve Working Group (www.pcwg.org) is an ad-hoc industry-led group to investigate the performance of wind turbines in real-world conditions. As part of ongoing experience-sharing exercises, machine learning has been proposed as a possible way to predict turbine performance. This presentation provides some background information about machine learning and how it might be implemented in the PCWG exercises.

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.

Ultrastructural characteristics of tau filaments in tauopathies: immuno-electron microscopic demonstration of tau filaments in tauopathies.

PubMed

Arima, Kunimasa

2006-10-01

The microtubule-associated protein tau aggregates into filaments in the form of neurofibrillary tangles, neuropil threads and argyrophilic grains in neurons, in the form of variable astrocytic tangles in astrocytes and in the form of coiled bodies and argyrophilic threads in oligodendrocytes. These tau filaments may be classified into two types, straight filaments or tubules with 9-18 nm diameters and "twisted ribbons" composed of two parallel aligned components. In the same disease, the fine structure of tau filaments in glial cells roughly resembles that in neurons. In sporadic tauopathies, individual tau filaments show characteristic sizes, shapes and arrangements, and therefore contribute to neuropathologic differential diagnosis. In frontotemporal dementias caused by tau gene mutations, variable filamentous profiles were observed in association with mutation sites and insoluble tau isoforms, including straight filaments or tubules, paired helical filament-like filaments, and twisted ribbons. Pre-embedding immunoelectron microscopic studies were carried out using anti-3-repeat tau and anti-4-repeat tau specific antibodies, RD3 and RD4. Straight tubules in neuronal and astrocytic Pick bodies were immunolabeled by the anti-3-repeat tau antibody. The anti-4-repeat tau antibody recognized abnormal tubules comprising neurofibrillary tangles, coiled bodies and argyrophilic threads in progressive supranuclear palsy (PSP) and corticobasal degeneration. In the pre-embedding immunoelectron microscopic study using the phosphorylated tau AT8 antibody, tuft-shaped astrocytes of PSP were found to be composed of bundles of abnormal tubules in processes and perikarya of protoplasmic astrocytes. In this study, the 3-repeat tau or 4-repeat tau epitope was detected in situ at the ultrastructural level in abnormal tubules in representative pathological lesions in Pick's disease, PSP and corticobasal degeneration.

Side-binding proteins modulate actin filament dynamics

PubMed Central

Crevenna, Alvaro H; Arciniega, Marcelino; Dupont, Aurélie; Mizuno, Naoko; Kowalska, Kaja; Lange, Oliver F; Wedlich-Söldner, Roland; Lamb, Don C

2015-01-01

Actin filament dynamics govern many key physiological processes from cell motility to tissue morphogenesis. A central feature of actin dynamics is the capacity of filaments to polymerize and depolymerize at their ends in response to cellular conditions. It is currently thought that filament kinetics can be described by a single rate constant for each end. In this study, using direct visualization of single actin filament elongation, we show that actin polymerization kinetics at both filament ends are strongly influenced by the binding of proteins to the lateral filament surface. We also show that the pointed-end has a non-elongating state that dominates the observed filament kinetic asymmetry. Estimates of flexibility as well as effects on fragmentation and growth suggest that the observed kinetic diversity arises from structural alteration. Tuning elongation kinetics by exploiting the malleability of the filament structure may be a ubiquitous mechanism to generate a rich variety of cellular actin dynamics. DOI: http://dx.doi.org/10.7554/eLife.04599.001 PMID:25706231

Role of Intermediate Filaments in Vesicular Traffic.

PubMed

Margiotta, Azzurra; Bucci, Cecilia

2016-04-25

Intermediate filaments are an important component of the cellular cytoskeleton. The first established role attributed to intermediate filaments was the mechanical support to cells. However, it is now clear that intermediate filaments have many different roles affecting a variety of other biological functions, such as the organization of microtubules and microfilaments, the regulation of nuclear structure and activity, the control of cell cycle and the regulation of signal transduction pathways. Furthermore, a number of intermediate filament proteins have been involved in the acquisition of tumorigenic properties. Over the last years, a strong involvement of intermediate filament proteins in the regulation of several aspects of intracellular trafficking has strongly emerged. Here, we review the functions of intermediate filaments proteins focusing mainly on the recent knowledge gained from the discovery that intermediate filaments associate with key proteins of the vesicular membrane transport machinery. In particular, we analyze the current understanding of the contribution of intermediate filaments to the endocytic pathway.

Boolean gates on actin filaments

NASA Astrophysics Data System (ADS)

Siccardi, Stefano; Tuszynski, Jack A.; Adamatzky, Andrew

2016-01-01

Actin is a globular protein which forms long polar filaments in the eukaryotic cytoskeleton. Actin networks play a key role in cell mechanics and cell motility. They have also been implicated in information transmission and processing, memory and learning in neuronal cells. The actin filaments have been shown to support propagation of voltage pulses. Here we apply a coupled nonlinear transmission line model of actin filaments to study interactions between voltage pulses. To represent digital information we assign a logical TRUTH value to the presence of a voltage pulse in a given location of the actin filament, and FALSE to the pulse's absence, so that information flows along the filament with pulse transmission. When two pulses, representing Boolean values of input variables, interact, then they can facilitate or inhibit further propagation of each other. We explore this phenomenon to construct Boolean logical gates and a one-bit half-adder with interacting voltage pulses. We discuss implications of these findings on cellular process and technological applications.

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.

Solid friction between soft filaments

DOE PAGES

Ward, Andrew; Hilitski, Feodor; Schwenger, Walter; ...

2015-03-02

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,more » can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. In conclusion, 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.« less

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.

A data-driven multi-model methodology with deep feature selection for short-term wind forecasting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Cong; Cui, Mingjian; Hodge, Bri-Mathias

With the growing wind penetration into the power system worldwide, improving wind power forecasting accuracy is becoming increasingly important to ensure continued economic and reliable power system operations. In this paper, a data-driven multi-model wind forecasting methodology is developed with a two-layer ensemble machine learning technique. The first layer is composed of multiple machine learning models that generate individual forecasts. A deep feature selection framework is developed to determine the most suitable inputs to the first layer machine learning models. Then, a blending algorithm is applied in the second layer to create an ensemble of the forecasts produced by firstmore » layer models and generate both deterministic and probabilistic forecasts. This two-layer model seeks to utilize the statistically different characteristics of each machine learning algorithm. A number of machine learning algorithms are selected and compared in both layers. This developed multi-model wind forecasting methodology is compared to several benchmarks. The effectiveness of the proposed methodology is evaluated to provide 1-hour-ahead wind speed forecasting at seven locations of the Surface Radiation network. Numerical results show that comparing to the single-algorithm models, the developed multi-model framework with deep feature selection procedure has improved the forecasting accuracy by up to 30%.« less

Recent observations of the formation of filaments

NASA Technical Reports Server (NTRS)

Martin, Sara F.

1986-01-01

Two examples of the formation of small filaments in H alpha are described and illustrated. In both cases, the formation is seen to be the spontaneous appearance of strands of absorbing mass that evolve from no previous structure. The initial development of the filaments appears to consist of the accumulation of these absorptive strands along approximately parallel paths in a channel between large-scale, opposite polarity magnetic fields on either side of the filaments. The strands exhibit continuous changes in shape and degree of absorption which can be due to successive condensations resulting in new strands, mass motions within the strands, and outflow of the mass from the strands. For at least several hours before the formation of both filaments, small-scale fragments of opposite polarity, line-of-sight magnetic flux adjacent to or immediately below the filaments, and at the ends of the filaments, were cancelling. This type of magnetic flux disappearance continued during the development of the filaments and is commonly observed in association with established filaments. Cancellation is interpreted as an important evolutionary change in the magnetic field that can lead to configurations suitable for the formation of filaments.

Interaction of Two Filaments in a Long Filament Channel Associated with Twin Coronal Mass Ejections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Ruisheng; Chen, Yao; Wang, Bing

Using the high-quality observations of the Solar Dynamics Observatory , we present the interaction of two filaments (F1 and F2) in a long filament channel associated with twin coronal mass ejections (CMEs) on 2016 January 26. Before the eruption, a sequence of rapid cancellation and emergence of the magnetic flux has been observed, which likely triggered the ascending of the west filament (F1). The east footpoints of rising F1 moved toward the east far end of the filament channel, accompanied by post-eruption loops and flare ribbons. This likely indicated a large-scale eruption involving the long filament channel, which resulted frommore » the interaction between F1 and the east filament (F2). Some bright plasma flew over F2, and F2 stayed at rest during the eruption, likely due to the confinement of its overlying lower magnetic field. Interestingly, the impulsive F1 pushed its overlying magnetic arcades to form the first CME, and F1 finally evolved into the second CME after the collision with the nearby coronal hole. We suggest that the interaction of F1 and the overlying magnetic field of F2 led to the merging reconnection that forms a longer eruptive filament loop. Our results also provide a possible picture of the origin of twin CMEs and show that the large-scale magnetic topology of the coronal hole is important for the eventual propagation direction of CMEs.« less

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

Powering of Hα Filaments by Cosmic Rays

NASA Astrophysics Data System (ADS)

Ruszkowski, Mateusz; Yang, H.-Y. Karen; Reynolds, Christopher S.

2018-05-01

Cluster cool cores possess networks of line-emitting filaments. These filaments are thought to originate via uplift of cold gas from cluster centers by buoyant active galactic nuclei (AGNs) bubbles, or via local thermal instability in the hot intracluster medium (ICM). Therefore, the filaments are either the signatures of AGN feedback or feeding of supermassive black holes. Despite being characterized by very short cooling times, the filaments are significant Hα emitters, which suggests that some process continuously powers these structures. Many cool cores host diffuse radio mini halos and AGN injecting radio plasma, suggesting that cosmic rays (CRs) and magnetic fields are present in the ICM. We argue that the excitation of Alfvén waves by CR streaming, and the replenishment of CR energy via accretion onto the filaments of high-plasma-β ICM characterized by low CR pressure support, can provide the adequate amount of heating to power and sustain the emission from these filaments. This mechanism does not require the CRs to penetrate the filaments, even if the filaments are magnetically isolated from the ambient ICM, and it may operate irrespectively of whether the filaments are dredged up from the center or form in situ in the ICM. This picture is qualitatively consistent with non-thermal line ratios seen in the cold filaments. Future X-ray observations of the iron line complex with XARM, Lynx, or Athena could help to test this model by providing constraints on the amount of CRs in the hot plasma that is cooling and accreting onto the filaments.

Solar filament material oscillations and drainage before eruption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bi, Yi; Jiang, Yunchun; Yang, Jiayan

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

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.

Prediction of Solar Eruptions Using Filament Metadata

NASA Astrophysics Data System (ADS)

Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal

2018-05-01

We perform a statistical analysis of erupting and non-erupting solar filaments to determine the properties related to the eruption potential. In order to perform this study, we correlate filament eruptions documented in the Heliophysics Event Knowledgebase (HEK) with HEK filaments that have been grouped together using a spatiotemporal tracking algorithm. The HEK provides metadata about each filament instance, including values for length, area, tilt, and chirality. We add additional metadata properties such as the distance from the nearest active region and the magnetic field decay index. We compare trends in the metadata from erupting and non-erupting filament tracks to discover which properties present signs of an eruption. We find that a change in filament length over time is the most important factor in discriminating between erupting and non-erupting filament tracks, with erupting tracks being more likely to have decreasing length. We attempt to find an ensemble of predictive filament metadata using a Random Forest Classifier approach, but find the probability of correctly predicting an eruption with the current metadata is only slightly better than chance.

Impact of wind generator infed on dynamic performance of a power system

NASA Astrophysics Data System (ADS)

Alam, Md. Ahsanul

Wind energy is one of the most prominent sources of electrical energy in the years to come. A tendency to increase the amount of electricity generation from wind turbine can be observed in many countries. One of the major concerns related to the high penetration level of the wind energy into the existing power grid is its influence on power system dynamic performance. In this thesis, the impact of wind generation system on power system dynamic performance is investigated through detailed dynamic modeling of the entire wind generator system considering all the relevant components. Nonlinear and linear models of a single machine as well as multimachine wind-AC system have been derived. For the dynamic model of integrated wind-AC system, a general transformation matrix is determined for the transformation of machine and network quantities to a common reference frame. Both time-domain and frequency domain analyses on single machine and multimachine systems have been carried out. The considered multimachine systems are---A 4 machine 12 bus system, and 10 machine 39 bus New England system. Through eigenvalue analysis, impact of asynchronous wind system on overall network damping has been quantified and modes responsible for the instability have been identified. Over with a number of simulation studies it is observed that for a induction generator based wind generation system, the fixed capacitor located at the generator terminal cannot normally cater for the reactive power demand during the transient disturbances like wind gust and fault on the system. For weak network connection, system instability may be initiated because of induction generator terminal voltage collapse under certain disturbance conditions. Incorporation of dynamic reactive power compensation scheme through either variable susceptance control or static compensator (STATCOM) is found to improve the dynamic performance significantly. Further improvement in transient profile has been brought in by

Unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions.

PubMed

Xu, B F; Wang, T G; Yuan, Y; Cao, J F

2015-02-28

A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional rotational effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Core filaments of the nuclear matrix

PubMed Central

1990-01-01

The nuclear matrix is concealed by a much larger mass of chromatin, which can be removed selectively by digesting nuclei with DNase I followed by elution of chromatin with 0.25 M ammonium sulfate. This mild procedure removes chromatin almost completely and preserves nuclear matrix morphology. The complete nuclear matrix consists of a nuclear lamina with an interior matrix composed of thick, polymorphic fibers and large masses that resemble remnant nucleoli. Further extraction of the nuclear matrices of HeLa or MCF-7 cells with 2 M sodium chloride uncovered a network of core filaments. A few dark masses remained enmeshed in the filament network and may be remnants of the nuclear matrix thick fibers and nucleoli. The highly branched core filaments had diameters of 9 and 13 nm measured relative to the intermediate filaments. They may serve as the core structure around which the matrix is constructed. The core filaments retained 70% of nuclear RNA. This RNA consisted both of ribosomal RNA precursors and of very high molecular weight hnRNA with a modal size of 20 kb. Treatment with RNase A removed the core filaments. When 2 M sodium chloride was used directly to remove chromatin after DNase I digestion without a preceding 0.25 M ammonium sulfate extraction, the core filaments were not revealed. Instead, the nuclear interior was filled with amorphous masses that may cover the filaments. This reflected a requirement for a stepwise increase in ionic strength because gradual addition of sodium chloride to a final concentration of 2 M without an 0.25 M ammonium sulfate extraction uncovered core filaments. PMID:2307700

Multiple Filamentation of Laser Pulses in a Glass

NASA Astrophysics Data System (ADS)

Apeksimov, D. V.; Bukin, O. A.; Golik, S. S.; Zemlyanov, A. A.; Iglakova, A. N.; Kabanov, A. M.; Kuchinskaya, O. I.; Matvienko, G. G.; Oshlakov, V. K.; Petrov, A. V.; Sokolova, E. B.

2016-03-01

Results are presented of experiments on investigation of the spatial characteristics of multi-filamentation region of giga- and terawatt pulses of a Ti:sapphire laser in a glass. Dependences are obtained of the coordinate of the beginning of filamentation region, number of filaments, their distribution along the laser beam axis, and length of filaments on the pulse power. It is shown that with increasing radiation power, the number of filaments in the multi-filamentation region decreases, whereas the filament diameter has a quasiconstant value for all powers realized in the experiments. It is shown that as a certain power of the laser pulse with Gauss energy density distribution is reached, the filamentation region acquires the shape of a hollow cone with apex directed toward the radiation source.

Size Effect on the Mechanical Properties of CF Winding Composite

NASA Astrophysics Data System (ADS)

Cui, Yuqing; Yin, Zhongwei

2017-12-01

Mechanical properties of filament winding composites are usually tested by NOL ring samples. Few people have studied the size effect of winding composite samples on the testing result of mechanical property. In this research, winding composite thickness, diameter, and geometry of NOL ring samples were prepared to investigate the size effect on the mechanical strength of carbon fiber (CF) winding composite. The CF T700, T1000, M40, and M50 were adopted for the winding composite, while the matrix was epoxy resin. Test results show that the tensile strength and ILSS of composites decreases monotonically with an increase of thickness from 1 mm to 4 mm. The mechanical strength of composite samples increases monotonically with the increase in diameter from 100 mm to 189 mm. The mechanical strength of composite samples with two flat sides are higher than those of cyclic annular samples.

Chirality and Magnetic Configurations of Solar Filaments

NASA Astrophysics Data System (ADS)

Ouyang, Y.; Zhou, Y. H.; Chen, P. F.; Fang, C.

2017-01-01

It has been revealed that the magnetic topology in the solar atmosphere displays hemispheric preference, I.e., helicity is mainly negative/positive in the northern/southern hemispheres, respectively. However, the strength of the hemispheric rule and its cyclic variation are controversial. In this paper, we apply a new method based on the filament drainage to 571 erupting filaments from 2010 May to 2015 December in order to determine the filament chirality and its hemispheric preference. It is found that 91.6% of our sample of erupting filaments follows the hemispheric rule of helicity sign. It is also found that the strength of the hemispheric preference of the quiescent filaments decreases slightly from ˜97% in the rising phase to ˜85% in the declining phase of solar cycle 24, whereas the strength of the intermediate filaments keeps a high value around 96 ± 4% at all times. Only the active-region filaments show significant variations. Their strength of the hemispheric rule rises from ˜63% to ˜95% in the rising phase, and keeps a high value of 82% ± 5% during the declining phase. Furthermore, during a half-year period around the solar maximum, their hemispheric preference totally vanishes. Additionally, we also diagnose the magnetic configurations of the filaments based on our indirect method and find that in our sample of erupting events, 89% are inverse-polarity filaments with a flux rope magnetic configuration, whereas 11% are normal-polarity filaments with a sheared arcade configuration.

Measuring Filament Orientation: A New Quantitative, Local Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, C.-E.; Cunningham, M. R.; Jones, P. A.

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitativelymore » on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”.« less

Measuring Filament Orientation: A New Quantitative, Local Approach

NASA Astrophysics Data System (ADS)

Green, C.-E.; Dawson, J. R.; Cunningham, M. R.; Jones, P. A.; Novak, G.; Fissel, L. M.

2017-09-01

The relative orientation between filamentary structures in molecular clouds and the ambient magnetic field provides insight into filament formation and stability. To calculate the relative orientation, a measurement of filament orientation is first required. We propose a new method to calculate the orientation of the one-pixel-wide filament skeleton that is output by filament identification algorithms such as filfinder. We derive the local filament orientation from the direction of the intensity gradient in the skeleton image using the Sobel filter and a few simple post-processing steps. We call this the “Sobel-gradient method.” The resulting filament orientation map can be compared quantitatively on a local scale with the magnetic field orientation map to then find the relative orientation of the filament with respect to the magnetic field at each point along the filament. It can also be used for constructing radial profiles for filament width fitting. The proposed method facilitates automation in analyses of filament skeletons, which is imperative in this era of “big data.”

Dynamics and mechanics of motor-filament systems

NASA Astrophysics Data System (ADS)

Kruse, K.; Jülicher, F.

2006-08-01

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

Laser femtoseconde, filamentation, nuage et orage

NASA Astrophysics Data System (ADS)

Courvoisier, F.; Boutou, V.; Kasparian, J.; Salmon, E.; Méjean, G.; Yu, J.; Wolf, J.-P.

2005-06-01

Les applications telles que le contrôle de foudre grâce aux filaments autoguidés générés par un laser femtoseconde nécessitent de propager un tel filament à travers des aérosols de gouttes d'eau. Nous montrons qu'un filament survit à son interaction avec une goutte de diamètre comparable au sien (95 μ m), ainsi qu'à des nuages d'épaisseur optique 3,2, soit 5% de transmission. Cette transmission est permise par la présence d'un “bain de photons” autour du filament. Ce bain forme un réservoir contenant une part importante de l'énergie du faisceau, en équilibre avec le filament, et favorisant son alimentation.

The Origins of Magnetic Structure in the Corona and Wind

NASA Technical Reports Server (NTRS)

Antiochos, Spiro K.

2010-01-01

One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at two special locations: photospheric polarity inversions lines. (non-potentiality observed as a filament channel) and coronal hole boundaries, (observed as the slow solar wind). This characteristic feature of the closed-field corona is highly unexpected given that its magnetic field is continuously tangled by photospheric motions. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. I propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries inversion lines and coronal holes, creating both filament channels and the slow wind. We describe how the helicity is injected and transported and calculate the relevant rates. I argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field. This work has been supported by the NASA HTP, SR&T, and LWS programs.

Hygrothermomechanical evaluation of transverse filament tape epoxy/polyester fiberglass composites

NASA Technical Reports Server (NTRS)

Lark, R. L.; Chamis, C. C.

1983-01-01

The static and cyclic load behavior of transverse filament tape (TFT) fiberglass/epoxy and TFY fiberglass/polyester composites, intended for use in the design of low-cost wind turbine blades, are presented. The data behavior is also evaluated with respect to predicted properties based on an integrated hygrothermomechanical response theory. Experimental TFT composite data were developed by the testing of laminates made by using composite layups typical of those used for the fabrication of TFT fiberglass wind turbine blades. Static properties include tension, compression, and interlaminar shear strengths at ambient conditions and at high humidity/elevated temperature conditions after a 500 hour exposure. Cyclic fatigue data were obtained using similar environmental conditions and a range of cyclic stresses. The environmental (temperature and moisture) and cyclic load effects on composite strength degradation are subsequently compared with the predictions obtained by using the composite life/durability theory. The results obtained show that the predicted hygrothermomechanical environmental effects on TFT composites are in good agreement with measured data for various properties including fatigue at different cyclic stresses.

Block-Module Electric Machines of Alternating Current

NASA Astrophysics Data System (ADS)

Zabora, I.

2018-03-01

The paper deals with electric machines having active zone based on uniform elements. It presents data on disk-type asynchronous electric motors with short-circuited rotors, where active elements are made by integrated technique that forms modular elements. Photolithography, spraying, stamping of windings, pressing of core and combined methods are utilized as the basic technological approaches of production. The constructions and features of operation for new electric machine - compatible electric machines-transformers are considered. Induction motors are intended for operation in hermetic plants with extreme conditions surrounding gas, steam-to-gas and liquid environment at a high temperature (to several hundred of degrees).

High-Strength Undiffused Brushless (HSUB) Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, John S; Tolbert, Leon M; Lee, Seong T

2007-01-01

This paper introduces a new high-strength undiffused brushless machine that transfers the stationary excitation magnetomotive force to the rotor without any brushes. For a conventional permanent magnet (PM) machine, the air gap flux density cannot be enhanced effectively but can be weakened. In the new machine, both the stationary excitation coil and the PM in the rotor produce an enhanced air gap flux. The PM in the rotor prevents magnetic flux diffusion between the poles and guides the reluctance flux path. The pole flux density in the air gap can be much higher than what the PM alone can produce.more » A high-strength machine is thus obtained. The air gap flux density can be weakened through the stationary excitation winding. This type of machine is particularly suitable for electric and hybrid-electric vehicle applications. Patents of this new technology are either granted or pending.« less

A tubular flux-switching permanent magnet machine

NASA Astrophysics Data System (ADS)

Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

2008-04-01

The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

CHIRALITY AND MAGNETIC CONFIGURATIONS OF SOLAR FILAMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ouyang, Y.; Zhou, Y. H.; Chen, P. F.

It has been revealed that the magnetic topology in the solar atmosphere displays hemispheric preference, i.e., helicity is mainly negative/positive in the northern/southern hemispheres, respectively. However, the strength of the hemispheric rule and its cyclic variation are controversial. In this paper, we apply a new method based on the filament drainage to 571 erupting filaments from 2010 May to 2015 December in order to determine the filament chirality and its hemispheric preference. It is found that 91.6% of our sample of erupting filaments follows the hemispheric rule of helicity sign. It is also found that the strength of the hemisphericmore » preference of the quiescent filaments decreases slightly from ∼97% in the rising phase to ∼85% in the declining phase of solar cycle 24, whereas the strength of the intermediate filaments keeps a high value around 96 ± 4% at all times. Only the active-region filaments show significant variations. Their strength of the hemispheric rule rises from ∼63% to ∼95% in the rising phase, and keeps a high value of 82% ± 5% during the declining phase. Furthermore, during a half-year period around the solar maximum, their hemispheric preference totally vanishes. Additionally, we also diagnose the magnetic configurations of the filaments based on our indirect method and find that in our sample of erupting events, 89% are inverse-polarity filaments with a flux rope magnetic configuration, whereas 11% are normal-polarity filaments with a sheared arcade configuration.« less

Measurement of aeroacoustic noise generated on wind turbine blades modified by trailing edge brushes

NASA Astrophysics Data System (ADS)

Asheim, Michael J.

As wind technology becomes a larger portion of the energy production picture, the problematic interactions between the machines and society will continue to become more pronounced. Of these problems, wind turbine noise is one of the most important to the future of wind turbine development. This study looks at the effect trailing edge brushes mounted on the 2 bladed Controls Advance Research Turbine (CART 2), located at the National Wind Technology Center, have on the overall acoustic and aerodynamic performance of the blades. The use of trailing edge brushes reduced the aeroacoustic noise by 1.0 to 5.0 dB over the baseline blade, depending on wind speed. This acoustic performance comes at a cost to the aerodynamic performance of the blades. The aerodynamic performance indicators, such as turbine power and root bending moments show that increased drag due to the brushes is the main contributor to the reduction in power production. An economic analysis also investigated how to best use noise mitigation devices to optimize acoustic, power performance and loads of a 600 kW baseline turbine, such as the CART 2. The analysis shows that the use of up a noise mitigation device of 4 dB is best used by increasing the rotor diameter and the power rating of the machine, from a 43.3 m diameter, 600 kW machine to a 68.8 m diameter, 886.7 kW machine. This increase resulted in an annual energy production increase of 414% when using a Rayleigh wind distribution with at a mean annual wind speed of 8.5 m/s. This is a reduction of cost of energy from 0.0463 per kWh to 0.0422 kWh. This reduction in energy production costs helps to explain the continuing trend of turbine machine growth in both rotor diameter and power rating.

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)

High-resolution Observations of Sympathetic Filament Eruptions by NVST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shangwei; Su, Yingna; Zhou, Tuanhui

We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope on 2015 October 15. The full picture of the eruptions is obtained from the corresponding Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA) observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts first, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions failed, since the filaments first rise up, thenmore » flow toward the south and merge into the southern large quiescent filament. We also observe repeated activations of mini filaments below the right filament after its eruption. Using magnetic field models constructed based on SDO /HMI magnetograms via the flux rope insertion method, we find that the left filament eruption is likely to be triggered by kink instability, while the weakening of overlying magnetic fields due to magnetic reconnection at an X-point between the two filament systems might play an important role in the onset of the right filament eruption.« less

Origin of Enigmatic Galactic-center Filaments Revealed

NASA Astrophysics Data System (ADS)

2004-06-01

were oriented perpendicular to the plane of the Galaxy, which would have aligned them with the Galaxy’s own magnetic field. "The problem with this hypothesis is that more recent images have revealed a population of weaker filaments oriented randomly in relation to the plane of the Galaxy," said Yusef-Zadeh. "This makes it difficult to explain the origin of the filaments by an organized Galactic magnetic field." In March and June of 2004, a team of astronomers using the GBT made images of the Galactic center at various wavelengths. The purpose of these surveys was to help identify radio features produced by hot gas (thermal emission) and those produced in magnetic fields (non-thermal emission). In general, thermal features radiate more strongly at shorter wavelengths and non-thermal at longer wavelengths. By comparing the GBT images with earlier VLA data taken of the same region, Yusef-Zadeh determined that a number of the non-thermal filaments seemed to connect to concentrated areas of thermal emission, which identify pockets of star formation. Galatic Center Combined radio image from the Very Large Array and Green Bank Telescope. The linear filaments near the top are some of the nonthermal radio filaments (NRFs) studied by the researchers. Other features, such as supernova remnants (SNRs) and the area surrounding our Galaxy's supermassive black hole (Sgr A) are shown. CREDIT: NRAO/AUI/NSF Yusef-Zadeh, et.al. (Click on Image for Larger Version) "What this showed us is that two seemingly disparate processes, thermal and non-thermal radio emission, can be created by the very same phenomenon," said Yusef-Zadeh. "In this case, that phenomenon is pockets of starburst activity." Yusef-Zadeh notes that the exact mechanism for how the areas of starburst generate the magnetic fields is still being investigated. "There are many ideas about the mechanism that generates these filaments," added Yusef-Zadeh, "but one possibility is that they are produced by the collision of winds

Reactive power generation in high speed induction machines by continuously occurring space-transients

NASA Astrophysics Data System (ADS)

Laithwaite, E. R.; Kuznetsov, S. B.

1980-09-01

A new technique of continuously generating reactive power from the stator of a brushless induction machine is conceived and tested on a 10-kw linear machine and on 35 and 150 rotary cage motors. An auxiliary magnetic wave traveling at rotor speed is artificially created by the space-transient attributable to the asymmetrical stator winding. At least two distinct windings of different pole-pitch must be incorporated. This rotor wave drifts in and out of phase repeatedly with the stator MMF wave proper and the resulting modulation of the airgap flux is used to generate reactive VA apart from that required for magnetization or leakage flux. The VAR generation effect increases with machine size, and leading power factor operation of the entire machine is viable for large industrial motors and power system induction generators.

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.

Principle and design of small-sized and high-definition x-ray machine

NASA Astrophysics Data System (ADS)

Zhao, Anqing

2010-10-01

The paper discusses the circuit design and working principles of VMOS PWM type 75KV10mA high frequency X-ray machine. The system mainly consists of silicon controlled rectifier, VMOS tube PWM type high-frequency and highvoltage inverter circuit, filament inverter circuit, high-voltage rectifier filter circuit and as X-ray tube. The working process can be carried out under the control of a single-chip microcomputer. Due to the small size and high resolution in imaging, the X-ray machine is mostly adopted for emergent medical diagnosis and specific circumstances where nondestructive tests are conducted.

Striation and convection in penumbral filaments

NASA Astrophysics Data System (ADS)

Spruit, H. C.; Scharmer, G. B.; Löfdahl, M. G.

2010-10-01

Observations with the 1-m Swedish Solar Telescope of the flows seen in penumbral filaments are presented. Time sequences of bright filaments show overturning motions strikingly similar to those seen along the walls of small isolated structures in the active regions. The filaments show outward propagating striations with inclination angles suggesting that they are aligned with the local magnetic field. We interpret it as the equivalent of the striations seen in the walls of small isolated magnetic structures. Their origin is then a corrugation of the boundary between an overturning convective flow inside the filament and the magnetic field wrapping around it. The outward propagation is a combination of a pattern motion due to the downflow observed along the sides of bright filaments, and the Evershed flow. The observed short wavelength of the striation argues against the existence of a dynamically significant horizontal field inside the bright filaments. Its intensity contrast is explained by the same physical effect that causes the dark cores of filaments, light bridges and “canals”. In this way striation represents an important clue to the physics of penumbral structure and its relation with other magnetic structures on the solar surface. We put this in perspective with results from the recent 3-D radiative hydrodynamic simulations. 4 movies are only available in electronic form at http://www.aanda.org

Electric power from vertical-axis wind turbines

NASA Astrophysics Data System (ADS)

Touryan, K. J.; Strickland, J. H.; Berg, D. E.

1987-12-01

Significant advancements have occurred in vertical axis wind turbine (VAWT) technology for electrical power generation over the last decade; in particular, well-proven aerodynamic and structural analysis codes have been developed for Darrieus-principle wind turbines. Machines of this type have been built by at least three companies, and about 550 units of various designs are currently in service in California wind farms. Attention is presently given to the aerodynamic characteristics, structural dynamics, systems engineering, and energy market-penetration aspects of VAWTs.

Apparatus For Laminating Segmented Core For Electric Machine

DOEpatents

Lawrence, Robert Anthony; Stabel, Gerald R

2003-06-17

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

Electrical machines and assemblies including a yokeless stator with modular lamination stacks

DOEpatents

Qu, Ronghai; Jansen, Patrick Lee; Bagepalli, Bharat Sampathkumar; Carl, Jr., Ralph James; Gadre, Aniruddha Dattatraya; Lopez, Fulton Jose

2010-04-06

An electrical machine includes a rotor with an inner rotor portion and an outer rotor portion, and a double-sided yokeless stator. The yokeless stator includes modular lamination stacks and is configured for radial magnetic flux flow. The double-sided yokeless stator is concentrically disposed between the inner rotor portion and the outer rotor portion of the electrical machine. Examples of particularly useful embodiments for the electrical machine include wind turbine generators, ship propulsion motors, switch reluctance machines and double-sided synchronous machines.

Methods for modeling cytoskeletal and DNA filaments

NASA Astrophysics Data System (ADS)

Andrews, Steven S.

2014-02-01

This review summarizes the models that researchers use to represent the conformations and dynamics of cytoskeletal and DNA filaments. It focuses on models that address individual filaments in continuous space. Conformation models include the freely jointed, Gaussian, angle-biased chain (ABC), and wormlike chain (WLC) models, of which the first three bend at discrete joints and the last bends continuously. Predictions from the WLC model generally agree well with experiment. Dynamics models include the Rouse, Zimm, stiff rod, dynamic WLC, and reptation models, of which the first four apply to isolated filaments and the last to entangled filaments. Experiments show that the dynamic WLC and reptation models are most accurate. They also show that biological filaments typically experience strong hydrodynamic coupling and/or constrained motion. Computer simulation methods that address filament dynamics typically compute filament segment velocities from local forces using the Langevin equation and then integrate these velocities with explicit or implicit methods; the former are more versatile and the latter are more efficient. Much remains to be discovered in biological filament modeling. In particular, filament dynamics in living cells are not well understood, and current computational methods are too slow and not sufficiently versatile. Although primarily a review, this paper also presents new statistical calculations for the ABC and WLC models. Additionally, it corrects several discrepancies in the literature about bending and torsional persistence length definitions, and their relations to flexural and torsional rigidities.

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

The Stokesian hydrodynamics of flexing, stretching filaments

NASA Astrophysics Data System (ADS)

Shelley, Michael J.; Ueda, Tetsuji

2000-11-01

A central element of many fundamental problems in physics and biology lies in the interaction of a viscous fluid with slender, elastic filaments. Examples arise in the dynamics of biological fibers, the motility of microscopic organisms, and in phase transitions of liquid crystals. When considering the dynamics on the scale of a single filament, the surrounding fluid can often be assumed to be inertialess and hence governed by the Stokes’ equations. A typical simplification then is to assume a local relation, along the filament, between the force per unit length exerted by the filament upon the fluid and the velocity of the filament. While this assumption can be justified through slender-body theory as the leading-order effect, this approximation is only logarithmically separated (in aspect ratio) from the next-order contribution capturing the first effects of non-local interactions mediated by the surrounding fluid; non-local interactions become increasingly important as a filament comes within proximity to itself, or another filament. Motivated by a pattern forming system in isotropic to smectic-A phase transitions, we consider the non-local Stokesian dynamics of a growing elastica immersed in a fluid. The non-local interactions of the filament with itself are included using a modification of the slender-body theory of Keller and Rubinow. This modification is asymptotically equivalent, and removes an instability of their formulation at small, unphysical length-scales. Within this system, the filament lives on a marginal stability boundary, driven by a continual process of growth and buckling. Repeated bucklings result in filament flex, which, coupled to the non-local interactions and mediated by elastic response, leads to the development of space-filling patterns. We develop numerical methods to solve this system accurately and efficiently, even in the presence of temporal stiffness and the close self-approach of the filament. While we have ignored many of the

Influence of winding construction on starter-generator thermal processes

NASA Astrophysics Data System (ADS)

Grachev, P. Yu; Bazarov, A. A.; Tabachinskiy, A. S.

2018-01-01

Dynamic processes in starter-generators features high winding are overcurrent. It can lead to insulation overheating and fault operation mode. For hybrid and electric vehicles, new high efficiency construction of induction machines windings is proposed. Stator thermal processes need be considered in the most difficult operation modes. The article describes construction features of new compact stator windings, electromagnetic and thermal models of processes in stator windings and explains the influence of innovative construction on thermal processes. Models are based on finite element method.

Utility operational experience on the NASA/DOE Mod-OA 200 kW Wind Turbine

NASA Technical Reports Server (NTRS)

Glasgow, J. C.; Robbins, W. H.

1979-01-01

The Mod-OA 200 kW Wind Turbine was designed and fabricated by the Lewis Research Center of the NASA under the direction of the U.S. Department of Energy. The project is a part of the Federal Wind Energy Program and is designed to obtain early wind turbine operation and performance data while gaining initial experience in the operation of large, horizontal axis wind turbines in typical utility environments. On March 6, 1978, the Mod-OA wind turbine was turned over to the Town of Clayton Light and Water Plant, Clayton, NM, for utility operation and on December 31, 1978 the machine had completed ten months of utility operation. This paper describes the machine and documents the recent operational experience at Clayton, NM.

Impact of Offshore Wind Power Integrated by VSC-HVDC on Power Angle Stability of Power Systems

NASA Astrophysics Data System (ADS)

Lu, Haiyang; Tang, Xisheng

2017-05-01

Offshore wind farm connected to grid by VSC-HVDC loses frequency support for power system, so adding frequency control in wind farm and VSC-HVDC system is an effective measure, but it will change wind farm VSC-HVDC’s transient stability on power system. Through theoretical analysis, concluding the relationship between equivalent mechanical power and electromagnetic power of two-machine system with the active power of wind farm VSC-HVDC, then analyzing the impact of wind farm VSC-HVDC with or without frequency control and different frequency control parameters on angle stability of synchronous machine by EEAC. The validity of theoretical analysis has been demonstrated through simulation in PSCAD/EMTDC.

The shape of strings to come: How topological defects twist, bend, and wrinkle filament bundles

NASA Astrophysics Data System (ADS)

Bruss, Isaac; Grason, Gregory

2015-03-01

Topological defects are crucial to the thermodynamics and structure of condensed matter systems. For instance, when incorporated into crystalline membranes like graphene, 5- and 7-fold disclinations produce conical- and saddle-like geometries respectively. A recently discovered mapping between the inter-filament spacing within a deformed bundle and the metric properties of curved surfaces, suggests previously unexplored parallels between the two, specifically in regards to how 2D patterning promotes 3D shape transitions. This discovery is poised to describe the structure of a host of filamentous materials-both biological and microfabricated-that exhibit distinctive shapes and packings. Motivated by the filamentous analogs to the conical and saddles shapes found in thin membranes, we investigate for the first time the interplay between defects in the cross section of a bundle and its global structure, using a combination of continuum elasticity theory and numerical simulation of cohesive bundles with a fixed packing topology. Focusing primarily on the instability response to disclinations, we predict a host of new equilibria structures, some of which are without direct parallel to the analogous membrane, including torsional wrinkling, radial kinking, and helical winding. Center for Hierarchical Manufacturing-CMMI 10-25020, NSF CAREER Award-DMR 09-55760, & UMass MRSEC.

Mini-thin filaments regulated by troponin–tropomyosin

PubMed Central

Gong, Huiyu; Hatch, Victoria; Ali, Laith; Lehman, William; Craig, Roger; Tobacman, Larry S.

2005-01-01

Striated muscle thin filaments contain hundreds of actin monomers and scores of troponins and tropomyosins. To study the cooperative mechanism of thin filaments, “mini-thin filaments” were generated by isolating particles nearly matching the minimal structural repeat of thin filaments: a double helix of actin subunits with each strand approximately seven actins long and spanned by a troponin–tropomyosin complex. One end of the particles was capped by a gelsolin (segment 1–3)–TnT fusion protein (substituting for normal TnT), and the other end was capped by tropomodulin. EM showed that the particles were 46 ± 9 nm long, with a knob-like mass attributable to gelsolin at one end. Average actin, tropomyosin, and gelsolin–troponin composition indicated one troponin–tropomyosin attached to each strand of the two-stranded actin filament. The minifilaments thus nearly represent single regulatory units of thin filaments. The myosin S1 MgATPase rate stimulated by the minifilaments was Ca2+-sensitive, indicating that single regulatory length particles are sufficient for regulation. Ca2+ bound cooperatively to cardiac TnC in conventional thin filaments but noncooperatively to cardiac TnC in minifilaments in the absence of myosin. This suggests that thin filament Ca2+-binding cooperativity reflects indirect troponin–troponin interactions along the long axis of conventional filaments, which do not occur in minifilaments. Despite noncooperative Ca2+ binding to minifilaments in the absence of myosin, Ca2+ cooperatively activated the myosin S1-particle ATPase rate. Two-stranded single regulatory units therefore may be sufficient for myosin-mediated Ca2+-binding cooperativity. Functional mini-thin filaments are well suited for biochemical and structural analysis of thin-filament regulation. PMID:15644437

Colloidal transport by active filaments

NASA Astrophysics Data System (ADS)

Manna, Raj Kumar; Kumar, P. B. Sunil; Adhikari, R.

2017-01-01

Enhanced colloidal transport beyond the limit imposed by diffusion is usually achieved through external fields. Here, we demonstrate the ballistic transport of a colloidal sphere using internal sources of energy provided by an attached active filament. The latter is modeled as a chain of chemo-mechanically active beads connected by potentials that enforce semi-flexibility and self-avoidance. The fluid flow produced by the active beads and the forces they mediate are explicitly taken into account in the overdamped equations of motion describing the colloid-filament assembly. The speed and efficiency of transport depend on the dynamical conformational states of the filament. We characterize these states using filament writhe as an order parameter and identify ones yielding maxima in speed and efficiency of transport. The transport mechanism reported here has a remarkable resemblance to the flagellar propulsion of microorganisms which suggests its utility in biomimetic systems.

Study of solar wind spectra by nonlinear waves interaction

NASA Astrophysics Data System (ADS)

Dwivedi, Navin; Sharma, Rampal; Narita, Yasuhito

2014-05-01

The nature of small-scale turbulent fluctuations in the solar wind (SW) turbulence is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations predict the evidence of the dominance of kinetic Alfvén waves (KAW) at sub-ion scales with frequency below than ion cyclotron frequency, while other studies suggest that the KAW mode cannot carry the turbulence cascade down to electron scales and that the whistler mode is more relevant. In the present work, nonlinear interaction of kinetic Alfvén wave with whistler wave is considered as one of the possible cause responsible for the solar wind turbulence. A set of coupled dimensionless equations are derived for the intermediate beta plasmas and the nonlinear interaction between these two wave modes has been studied. As a consequence of ponderomotive nonlinearity, the pump KAW becomes filamented when its power exceeds the threshold for the filamentation instability. Whistler is considered to be weak and thus doesn't have enough intensity to initiate its own localization. It gets localized while propagating through the density channel created by KAW localization. In addition, spectral scales of power spectra of KAW and whistler are also calculated. The steeper spectra are found with scaling greater than -5/3. This type of nonlinear interaction between different wave modes and steeper spectra is one of the reasons for the solar wind turbulence and particles acceleration. This work is partially supported by DST (India) and FP7/STORM (313038)

Convergent-Filament Nonmechanical Pump

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr.

1989-01-01

Simple device induces small flow of liquid without help of moving parts, in presence or absence of gravity. Drops of liquid move on filaments from wide end of cone to narrow end. Gradually blend with drops on adjacent filaments to form large drops with menisci. Important use expected to be returning liquid condensate in heat pipes, and collection of samples from clouds or fog.

Ultraminiature broadband light source with spiral shaped filament

NASA Technical Reports Server (NTRS)

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

Graphene-based filament material for thermal ionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hewitt, J.; Shick, C.; Siegfried, M.

The use of graphene oxide materials for thermal ionization mass spectrometry analysis of plutonium and uranium has been investigated. Filament made from graphene oxide slurries have been 3-D printed. A method for attaching these filaments to commercial thermal ionization post assemblies has been devised. Resistive heating of the graphene based filaments under high vacuum showed stable operation in excess of 4 hours. Plutonium ion production has been observed in an initial set of filaments spiked with the Pu 128 Certified Reference Material.

Filament eruption connected to protospheric activity

NASA Technical Reports Server (NTRS)

Simon, G.; Gesztelyi, L.; Schmieder, B.; Mein, N

1986-01-01

Two cases of activation of filaments that occured in regions of intense magnetic activity was studied. The simultaneous observations from Debrecen Observatory (white light and H alpha filtergram), and from Meudon Observatory (magnetogram, MSDP dopplergram and intensity maps in H alpha) gave a complementary set of data from which can be produced evidence of the influence of the photospheric magnetic field on the destabilization process of the filaments. On June 22, 1980, the eruption of the filament is associated with the motion of pores, which are manifestations of emerging flux knots. On September 3, 1980, the twisting motions in the filament are associated to the birth of a pore in its neighborhood. These observations are discussed.

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

Thick Filament Protein Network, Functions, and Disease Association.

PubMed

Wang, Li; Geist, Janelle; Grogan, Alyssa; Hu, Li-Yen R; Kontrogianni-Konstantopoulos, Aikaterini

2018-03-13

Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018. Copyright © 2018 American Physiological Society. All rights reserved.

Wind turbine generator rotor blade concepts with low cost potential

NASA Technical Reports Server (NTRS)

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

1977-01-01

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

Wind-turbine-generator rotor-blade concepts with low-cost potential

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Dynamics of contracting surfactant-covered filaments

NASA Astrophysics Data System (ADS)

Kamat, Pritish; Thete, Sumeet; Xu, Qi; Basaran, Osman

2013-11-01

When drops are produced from a nozzle, a thin liquid thread connects the primary drop that is about to form to the rest of the liquid in the nozzle. Often, the thread becomes disconnected from both the primary drop and the remnant liquid mass hanging from the nozzle and thereby gives rise to a free filament. Due to surface tension, the free filament then contracts or recoils. During recoil, the filament can either contract into a single satellite droplet or break up into several small satellites. Such satellite droplets are undesirable in applications where they can, for example, cause misting in a manufacturing environment and mar product quality in ink-jet printing. In many applications, the filaments are coated with a monolayer of surfactant. In this work, we study the dynamics of contraction of slender filaments of a Newtonian fluid that are covered with a monolayer of surfactant when the surrounding fluid is a passive gas. Taking advantage of the fact that the filaments are long and slender, we use a 1D-slender-jet approximation of the governing system of equations consisting of the Navier-Stokes system and the convection-diffusion equation for surfactant transport. We solve the 1D system of equations by a finite element based numerical method.

INTERACTION OF TWO FILAMENT CHANNELS OF DIFFERENT CHIRALITIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, Navin Chandra; Magara, Tetsuya; Moon, Yong-Jae

2016-07-10

We present observations of the interactions between the two filament channels of different chiralities and associated dynamics that occurred during 2014 April 18–20. While two flux ropes of different helicity with parallel axial magnetic fields can only undergo a bounce interaction when they are brought together, the observations at first glance show that the heated plasma is moving from one filament channel to the other. The SDO /AIA 171 Å observations and the potential-field source-surface magnetic field extrapolation reveal the presence of a fan-spine magnetic configuration over the filament channels with a null point located above them. Three different eventsmore » of filament activations, partial eruptions, and associated filament channel interactions have been observed. The activation initiated in one filament channel seems to propagate along the neighboring filament channel. We believe that the activation and partial eruption of the filaments brings the field lines of flux ropes containing them closer to the null point and triggers the magnetic reconnection between them and the fan-spine magnetic configuration. As a result, the hot plasma moves along the outer spine line toward the remote point. Utilizing the present observations, for the first time we have discussed how two different-chirality filament channels can interact and show interrelation.« less

Two-step solar filament eruptions

NASA Astrophysics Data System (ADS)

Filippov, B.

2018-04-01

Coronal mass ejections (CMEs) are closely related to eruptive filaments and usually are the continuation of the same eruptive process into the upper corona. There are failed filament eruptions when a filament decelerates and stops at some greater height in the corona. Sometimes the filament after several hours starts to rise again and develops into the successful eruption with a CME formation. We propose a simple model for the interpretation of such two-step eruptions in terms of equilibrium of a flux rope in a two-scale ambient magnetic field. The eruption is caused by a slow decrease of the holding magnetic field. The presence of two critical heights for the initiation of the flux-rope vertical instability allows the flux rope to stay after the first jump some time in a metastable equilibrium near the second critical height. If the decrease of the ambient field continues, the next eruption step follows.

METHOD OF MAKING TUNGSTEN FILAMENTS

DOEpatents

Frazer, J.W.

1962-12-18

A method of making tungsten filaments is described in which the tungsten is completely free of isotope impurities in the range of masses 234 to 245 for use in mass spectrometers. The filament comprises a tantalum core generally less than 1 mil in diameter having a coating of potassium-free tantalum-diffused tungsten molecularly bonded thereto. In the preferred process of manufacture a short, thin tantalum filament is first mounted between terminal posts mounted in insulated relation through a backing plate. The tungsten is most conveniently vapor plated onto the tantalum by a tungsten carbonyl vapor decomposition method having a critical step because of the tendency of the tantalum to volatilize at the temperature of operntion of the filament. The preferred recipe comprises volatilizing tantalum by resistance henting until the current drops by about 40%, cutting the voltage back to build up the tungsten, and then gradually building the temperature back up to balance the rate of tungsten deposition with the rate of tantalum volatilization. (AEC)

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 Hα 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 Hα 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 Hα 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

Plasma Brightenings in a Failed Solar Filament Eruption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y.; Ding, M. D., E-mail: yingli@nju.edu.cn

Failed filament eruptions are solar eruptions that are not associated with coronal mass ejections. In a failed filament eruption, the filament materials usually show some ascending and falling motions as well as generating bright EUV emissions. Here we report a failed filament eruption (SOL2016-07-22) that occurred in a quiet-Sun region observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory . In this event, the filament spreads out but gets confined by the surrounding magnetic field. When interacting with the ambient magnetic field, the filament material brightens up and flows along the magnetic field lines through the coronamore » to the chromosphere. We find that some materials slide down along the lifting magnetic structure containing the filament and impact the chromosphere, and through kinetic energy dissipation, cause two ribbon-like brightenings in a wide temperature range. There is evidence suggesting that magnetic reconnection occurs between the filament magnetic structure and the surrounding magnetic fields where filament plasma is heated to coronal temperatures. In addition, thread-like brightenings show up on top of the erupting magnetic fields at low temperatures, which might be produced by an energy imbalance from a fast drop of radiative cooling due to plasma rarefaction. Thus, this single event of a failed filament eruption shows the existence of a variety of plasma brightenings that may be caused by completely different heating mechanisms.« less

Flow widening through a Darrieus wind turbine - Theory and experiment

NASA Astrophysics Data System (ADS)

Comolet, R.; Harajli, I.; Mercier Des Rochettes, P.; Yeznasni, A.

1982-11-01

A two-dimensional multiple stream tube model is developed for the air flow through a Darrieus wind turbine. The model is configured to account for the widening of the flux tubes as they cross the interior of the actuator disk. Note is made of the lateral broadening of the flow as it moves through the area, leaving a turbulent wake. A relation is defined between the variation in the kinetic energy of the flow and the aerodynamic forces acting on the blades. The global efficiency and the power output of the machine are calculated. Experimental results are reported for a machine equipped with two NACA 0015 blades, each 110 cm long and with a 10 cm chord. The Darrieus had a 1 m diam and was tested in a wind tunnel at wind speeds of 0-18 m/sec. Soap bubbles inflated with He were used for visualization. Power output was found to match prediction. The model is recommended for use in calculating the forces acting on the machine and studying vibration and fatigue causative mechanisms.

Fabrication of PLA Filaments and its Printable Performance

NASA Astrophysics Data System (ADS)

Liu, Wenjie; Zhou, Jianping; Ma, Yuming; Wang, Jie; Xu, Jie

2017-12-01

Fused deposition modeling (FDM) is a typical 3D printing technology and preparation of qualified filaments is the basis. In order to prepare polylactic acid (PLA) filaments suitable for personalized FDM 3D printing, this article investigated the effect of factors such as extrusion temperature and screw speed on the diameter, surface roughness and ultimate tensile stress of the obtained PLA filaments. The optimal process parameters for fabrication of qualified filaments were determined. Further, the printable performance of the obtained PLA filaments for 3D objects was preliminarily explored.

Terahertz waves radiated from two noncollinear femtosecond plasma filaments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Hai-Wei; Hoshina, Hiromichi; Otani, Chiko, E-mail: otani@riken.jp

2015-11-23

Terahertz (THz) waves radiated from two noncollinear femtosecond plasma filaments with a crossing angle of 25° are investigated. The irradiated THz waves from the crossing filaments show a small THz pulse after the main THz pulse, which was not observed in those from single-filament scheme. Since the position of the small THz pulse changes with the time-delay of two filaments, this phenomenon can be explained by a model in which the small THz pulse is from the second filament. The denser plasma in the overlap region of the filaments changes the movement of space charges in the plasma, thereby changingmore » the angular distribution of THz radiation. As a result, this schematic induces some THz wave from the second filament to propagate along the path of the THz wave from the first filament. Thus, this schematic alters the direction of the THz radiation from the filamentation, which can be used in THz wave remote sensing.« less

Aerogel-supported filament

DOEpatents

Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.

1995-01-01

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

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.

A comparison study of a solar active-region eruptive filament and a neighboring non-eruptive filament

NASA Astrophysics Data System (ADS)

Jiang, Chao-Wei; Wu, Shi-Tsan; Feng, Xue-Shang; Hu, Qiang

2016-01-01

Solar active region (AR) 11283 is a very magnetically complex region and it has produced many eruptions. However, there exists a non-eruptive filament in the plage region just next to an eruptive one in the AR, which gives us an opportunity to perform a comparison analysis of these two filaments. The coronal magnetic field extrapolated using our CESE-MHD-NLFFF code reveals that two magnetic flux ropes (MFRs) exist in the same extrapolation box supporting these two filaments, respectively. Analysis of the magnetic field shows that the eruptive MFR contains a bald-patch separatrix surface (BPSS) cospatial very well with a pre-eruptive EUV sigmoid, which is consistent with the BPSS model for coronal sigmoids. The magnetic dips of the non-eruptive MFRs match Hα observation of the non-eruptive filament strikingly well, which strongly supports the MFR-dip model for filaments. Compared with the non-eruptive MFR/filament (with a length of about 200 Mm), the eruptive MFR/filament is much smaller (with a length of about 20 Mm), but it contains most of the magnetic free energy in the extrapolation box and holds a much higher free energy density than the non-eruptive one. Both the MFRs are weakly twisted and cannot trigger kink instability. The AR eruptive MFR is unstable because its axis reaches above a critical height for torus instability, at which the overlying closed arcades can no longer confine the MFR stably. On the contrary, the quiescent MFR is very firmly held by its overlying field, as its axis apex is far below the torus-instability threshold height. Overall, this comparison investigation supports that an MFR can exist prior to eruption and the ideal MHD instability can trigger an MFR eruption.

High-Strength Undiffused Brushless (HSUB) Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, John S; Lee, Seong T; Tolbert, Leon M

2008-01-01

This paper introduces a new high-strength undiffused brushless machine that transfers the stationary excitation magnetomotive force to the rotor without any brushes. For a conventional permanent magnet (PM) machine, the air-gap flux density cannot be enhanced effectively but can be weakened. In the new machine, both the stationary excitation coil and the PM in the rotor produce an enhanced air-gap flux. The PM in the rotor prevents magnetic-flux diffusion between the poles and guides the reluctance flux path. The pole flux density in the air gap can be much higher than what the PM alone can produce. A high-strength machinemore » is thus obtained. The air-gap flux density can be weakened through the stationary excitation winding. This type of machine is particularly suitable for electric and hybrid-electric vehicle applications. Patents of this new technology are either granted or pending.« less

Effects of pole flux distribution in a homopolar linear synchronous machine

NASA Astrophysics Data System (ADS)

Balchin, M. J.; Eastham, J. F.; Coles, P. C.

1994-05-01

Linear forms of synchronous electrical machine are at present being considered as the propulsion means in high-speed, magnetically levitated (Maglev) ground transportation systems. A homopolar form of machine is considered in which the primary member, which carries both ac and dc windings, is supported on the vehicle. Test results and theoretical predictions are presented for a design of machine intended for driving a 100 passenger vehicle at a top speed of 400 km/h. The layout of the dc magnetic circuit is examined to locate the best position for the dc winding from the point of view of minimum core weight. Measurements of flux build-up under the machine at different operating speeds are given for two types of secondary pole: solid and laminated. The solid pole results, which are confirmed theoretically, show that this form of construction is impractical for high-speed drives. Measured motoring characteristics are presented for a short length of machine which simulates conditions at the leading and trailing ends of the full-sized machine. Combination of the results with those from a cylindrical version of the machine make it possible to infer the performance of the full-sized traction machine. This gives 0.8 pf and 0.9 efficiency at 300 km/h, which is much better than the reported performance of a comparable linear induction motor (0.52 pf and 0.82 efficiency). It is therefore concluded that in any projected high-speed Maglev systems, a linear synchronous machine should be the first choice as the propulsion means.

Wind energy - A utility perspective

NASA Astrophysics Data System (ADS)

Fung, K. T.; Scheffler, R. L.; Stolpe, J.

1981-03-01

Broad consideration is given to the siting, demand, capital and operating cost and wind turbine design factors involved in a utility company's incorporation of wind powered electrical generation into existing grids. With the requirements of the Southern California Edison service region in mind, it is concluded that although the economic and legal climate for major investments in windpower are favorable, the continued development of large only wind turbine machines (on the scale of NASA's 2.5 MW Mod-2 design) is imperative in order to reduce manpower and maintenance costs. Stress is also put on the use of demonstration projects for both vertical and horizontal axis devices, in order to build up operational experience and confidence.

Experimental Investigation of Superconducting Synchronous Machines

DTIC Science & Technology

The report details the design and testing of a synchronous motor with superconducting field and armature windings. Data are furnished on the...as a generator with its armature in LN2 and in the superconducting state are given. Data are given on the machine operated as a synchronous motor. The

Topologies for three-phase wound-field salient rotor switched-flux machines for HEV applications

NASA Astrophysics Data System (ADS)

Khan, Faisal; Sulaiman, Erwan; Ahmad, Md Zarafi; Husin, Zhafir Aizat; Mazlan, Mohamed Mubin Aizat

2015-05-01

Wound-field switched-flux machines (WFSFM) have an intrinsic simplicity and high speed that make them well suited to many hybrid electric vehicle (HEV) applications. However, overlap armature and field windings raised the copper losses in these machines. Furthermore, in previous design segmented-rotor is used which made the rotor less robust. To overcome these problems, this paper presents novel topologies for three-phase wound-field switched-flux machines. Both armature and field winding are located on the stator and rotor is composed of only stack of iron. Non-overlap armature and field windings and toothed-rotor are the clear advantages of these topologies as the copper losses gets reduce and rotor becomes more robust. Design feasibility and performance analysis of 12 slots and different rotor pole numbers are examined on the basis of coil arrangement test, peak armature flux linkage, back emf, cogging torque and average torque by using Finite Element Analysis(FEA).

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.

The Connection Between Solar Coronal Cavities and Solar Filaments

NASA Astrophysics Data System (ADS)

Zawadzki, B.; Karna, N.; Prchlik, J.; Reeves, K.; Kempton, D.; Angryk, R.

2017-12-01

Filaments are structures in the solar corona made up of relatively cool, dense, partially ionized plasma. Coronal cavities, circular or elliptical regions of low plasma density, are observed above prominences on the solar limb when viewed in EUV and white light coronal images. Since most filament/cavity eruptions lead to a coronal mass ejection (CME), determining the likelihood of an eruption event will improve our ability to predict space weather. We examine SDO/AIA cavity metadata and HEK filament metadata to determine which cavities are associated with which filaments from 2012 to 2015. Our study involved 140 cavities and 368 filaments that appeared poleward of +-30 degrees. We categorized the cavities and filaments based on the stability of the structures, defined by whether or not the cavity and filament exist long enough to track fully across the solar disk. Using these categories we perform a statistical study on various filament qualities within the metadata. Our findings indicate that filaments with cavities are observed more often at high latitude in compared to filaments without cavities. Moreover, our study indicates that a statistically significant difference exists between the filament length and tilt distributions for certain categories. This work supported by the NSF-REU solar physics program at SAO, grant number AGS-1560313, and the NSF-DIBBS project, grant number ACI-1443061.

Reliability and quality assurance on the MOD 2 wind system

NASA Technical Reports Server (NTRS)

Mason, W. E. B.; Jones, B. G.

1981-01-01

The Safety, Reliability, and Quality Assurance (R&QA) approach developed for the largest wind turbine generator, the Mod 2, is described. The R&QA approach assures that the machine is not hazardous to the public or to the operating personnel, is operated unattended on a utility grid, demonstrates reliable operation, and helps establish the quality assurance and maintainability requirements for future wind turbine projects. The significant guideline consisted of a failure modes and effects analysis (FMEA) during the design phase, hardware inspections during parts fabrication, and three simple documents to control activities during machine construction and operation.

The Oregon State University wind studies. [economic feasibility of windpowered generators

NASA Technical Reports Server (NTRS)

Wilson, R. E.

1973-01-01

The economic feasibility of commercial use of wind generated power in selected areas of Oregon is assessed. A number of machines for generating power have been examined. These include the Savonius rotor, translators, conventional wind turbines, the circulation controlled rotor and the vertical axis winged turbine. Of these machines, the conventional wind turbine and the vertical axis winged turbine show the greatest promise on the basis of the power developed per unit of rotor blade area. Attention has been focused on the structural and fatigue analysis of rotors since the economics of rotary winged, wind generated power depends upon low cost, long lifetime rotors. Analysis of energy storage systems and tower design has also been undertaken. An economic means of energy storage has not been found to date. Tower design studies have produced cost estimates that are in general agreement with the cost of the updated Putnam 110-foot tower.

Smoothing Control of Wind Farm Output by Using Kinetic Energy of Variable Speed Wind Power Generators

NASA Astrophysics Data System (ADS)

Sato, Daiki; Saitoh, Hiroumi

This paper proposes a new control method for reducing fluctuation of power system frequency through smoothing active power output of wind farm. The proposal is based on the modulation of rotaional kinetic energy of variable speed wind power generators through power converters between permanent magnet synchronous generators (PMSG) and transmission lines. In this paper, the proposed control is called Fluctuation Absorption by Flywheel Characteristics control (FAFC). The FAFC can be easily implemented by adding wind farm output signal to Maximum Power Point Tracking control signal through a feedback control loop. In order to verify the effectiveness of the FAFC control, a simulation study was carried out. In the study, it was assumed that the wind farm consisting of PMSG type wind power generator and induction machine type wind power generaotors is connected with a power sysem. The results of the study show that the FAFC control is a useful method for reducing the impacts of wind farm output fluctuation on system frequency without additional devices such as secondary battery.

Brownian microhydrodynamics of active filaments.

PubMed

Laskar, Abhrajit; Adhikari, R

2015-12-21

Slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts. The interplay between the spontaneous fluid flow, Brownian motion, and the elasticity of the body presents a challenging fluid-structure interaction problem. Here, we model this problem by approximating the slender body as an elastic filament that can impose non-equilibrium velocities or stresses at the fluid-structure interface. We derive equations of motion for such an active filament by enforcing momentum conservation in the fluid-structure interaction and assuming slow viscous flow in the fluid. The fluid-structure interaction is obtained, to any desired degree of accuracy, through the solution of an integral equation. A simplified form of the equations of motion, which allows for efficient numerical solutions, is obtained by applying the Kirkwood-Riseman superposition approximation to the integral equation. We use this form of equation of motion to study dynamical steady states in free and hinged minimally active filaments. Our model provides the foundation to study collective phenomena in momentum-conserving, Brownian, active filament suspensions.

Remote electrical arc suppression by laser filamentation.

PubMed

Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre

2015-11-02

We investigate the interaction of narrow plasma channels formed in the filamentation of ultrashort laser pulses, with a DC high voltage. The laser filaments prevent electrical arcs by triggering corona that neutralize the high-voltage electrodes. This phenomenon, that relies on the electric field modulation and free electron release around the filament, opens new prospects to lightning and over-voltage mitigation.

Spontaneous beating and synchronization of extensile active filament

NASA Astrophysics Data System (ADS)

Sarkar, Debarati; Thakur, Snigdha

2017-04-01

We simulate a semi-flexible active filament that exhibits spontaneous oscillations on clamping and show self-propulsion when left free. The activity on the filament relies on the nano-dimers distributed at regular intervals along the chain. With an emphasis on the spontaneous beating of a clamped filament, we demonstrate that the two competing forces necessary for oscillation are the elastic forces due to polymer rigidity and the active forces due to chemical activity. In addition, we also study the synchronization of two extensile filaments and the role played by non-local hydrodynamic interactions. We observe a phase lock scenario between the filaments during their synchronous motion.

Hydrodynamic interaction induced spontaneous rotation of coupled active filaments.

PubMed

Jiang, Huijun; Hou, Zhonghuai

2014-12-14

We investigate the coupled dynamics of active filaments with long range hydrodynamic interactions (HI). Remarkably, we find that filaments can rotate spontaneously under the same conditions in which a single filament alone can only move in translation. Detailed analysis reveals that the emergence of coupled rotation originates from an asymmetric flow field associated with HI which breaks the symmetry of translational motion when filaments approach. The breaking is then further stabilized by HI to form self-sustained coupled rotation. Intensive simulations show that coupled rotation forms easily when one filament tends to collide with the front-half of the other. For head-to-tail approaching, we observe another interesting HI-induced coupled motion, where filaments move together in the form of one following the other. Moreover, the radius of coupled rotation increases exponentially as the rigidity of the filament increases, which suggests that HI are also important for the alignment of rigid-rod-like filaments which has been assumed to be solely a consequence of direct collisions.

Aerogel-supported filament

DOEpatents

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

1995-05-16

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

Star-forming Filament Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, Philip C., E-mail: pmyers@cfa.harvard.edu

2017-03-20

New models of star-forming filamentary clouds are presented in order to quantify their properties and to predict their evolution. These 2D axisymmetric models describe filaments that have no core, one low-mass core, and one cluster-forming core. They are based on Plummer-like cylinders and spheroids that are bounded by a constant-density surface of finite extent. In contrast to 1D Plummer-like models, they have specific values of length and mass, they approximate observed column density maps, and their distributions of column density ( N -pdfs) are pole-free. Each model can estimate the star-forming potential of a core-filament system by identifying the zonemore » of gas dense enough to form low-mass stars and by counting the number of enclosed thermal Jeans masses. This analysis suggests that the Musca central filament may be near the start of its star-forming life, with enough dense gas to make its first ∼3 protostars, while the Coronet filament is near the midpoint of its star formation, with enough dense gas to add ∼8 protostars to its ∼20 known stars. In contrast, L43 appears to be near the end of its star-forming life, since it lacks enough dense gas to add any new protostars to the two young stellar objectsalready known.« less

Wire electric-discharge machining and other fabrication techniques

NASA Technical Reports Server (NTRS)

Morgan, W. H.

1983-01-01

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

Objective estimation of tropical cyclone innercore surface wind structure using infrared satellite images

NASA Astrophysics Data System (ADS)

Zhang, Changjiang; Dai, Lijie; Ma, Leiming; Qian, Jinfang; Yang, Bo

2017-10-01

An objective technique is presented for estimating tropical cyclone (TC) innercore two-dimensional (2-D) surface wind field structure using infrared satellite imagery and machine learning. For a TC with eye, the eye contour is first segmented by a geodesic active contour model, based on which the eye circumference is obtained as the TC eye size. A mathematical model is then established between the eye size and the radius of maximum wind obtained from the past official TC report to derive the 2-D surface wind field within the TC eye. Meanwhile, the composite information about the latitude of TC center, surface maximum wind speed, TC age, and critical wind radii of 34- and 50-kt winds can be combined to build another mathematical model for deriving the innercore wind structure. After that, least squares support vector machine (LSSVM), radial basis function neural network (RBFNN), and linear regression are introduced, respectively, in the two mathematical models, which are then tested with sensitivity experiments on real TC cases. Verification shows that the innercore 2-D surface wind field structure estimated by LSSVM is better than that of RBFNN and linear regression.

Mid-infrared laser filaments in the atmosphere

PubMed Central

Mitrofanov, A. V.; Voronin, A. A.; Sidorov-Biryukov, D. A.; Pugžlys, A.; Stepanov, E. A.; Andriukaitis, G.; Flöry, T.; Ališauskas, S.; Fedotov, A. B.; Baltuška, A.; Zheltikov, A. M.

2015-01-01

Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single filament, has been ongoing over two decades, during which time the available laser sources limited filamentation experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 μm, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single filament. Our studies reveal unique properties of mid-infrared filaments, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared. PMID:25687621

Prokaryotic cytoskeletons: protein filaments organizing small cells.

PubMed

Wagstaff, James; Löwe, Jan

2018-04-01

Most, if not all, bacterial and archaeal cells contain at least one protein filament system. Although these filament systems in some cases form structures that are very similar to eukaryotic cytoskeletons, the term 'prokaryotic cytoskeletons' is used to refer to many different kinds of protein filaments. Cytoskeletons achieve their functions through polymerization of protein monomers and the resulting ability to access length scales larger than the size of the monomer. Prokaryotic cytoskeletons are involved in many fundamental aspects of prokaryotic cell biology and have important roles in cell shape determination, cell division and nonchromosomal DNA segregation. Some of the filament-forming proteins have been classified into a small number of conserved protein families, for example, the almost ubiquitous tubulin and actin superfamilies. To understand what makes filaments special and how the cytoskeletons they form enable cells to perform essential functions, the structure and function of cytoskeletal molecules and their filaments have been investigated in diverse bacteria and archaea. In this Review, we bring these data together to highlight the diverse ways that linear protein polymers can be used to organize other molecules and structures in bacteria and archaea.

A Method for 3D-Reconstruction of a Muscle Thick Filament Using the Tilt Series Images of a Single Filament Electron Tomogram

PubMed Central

Márquez, G.; Pinto, A.; Alamo, L.; Baumann, B.; Ye, F.; Winkler, H.; Taylor, K.; Padrón, R.

2014-01-01

Summary Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament –calculated without any image averaging and/or imposition of helical symmetry- only reveals MIH motifs infrequently. This is –to our knowledge- the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. PMID:24727133

A method for 3D-reconstruction of a muscle thick filament using the tilt series images of a single filament electron tomogram.

PubMed

Márquez, G; Pinto, A; Alamo, L; Baumann, B; Ye, F; Winkler, H; Taylor, K; Padrón, R

2014-05-01

Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament - calculated without any image averaging and/or imposition of helical symmetry - only reveals MIH motifs infrequently. This is - to our knowledge - the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. Copyright © 2014 Elsevier Inc. All rights reserved.

Direct observation of subunit exchange along mature vimentin intermediate filaments.

PubMed

Nöding, Bernd; Herrmann, Harald; Köster, Sarah

2014-12-16

Actin filaments, microtubules, and intermediate filaments (IFs) are central elements of the metazoan cytoskeleton. At the molecular level, the assembly mechanism for actin filaments and microtubules is fundamentally different from that of IFs. The former two types of filaments assemble from globular proteins. By contrast, IFs assemble from tetrameric complexes of extended, half-staggered, and antiparallel oriented coiled-coils. These tetramers laterally associate into unit-length filaments; subsequent longitudinal annealing of unit-length filaments yields mature IFs. In vitro, IFs form open structures without a fixed number of tetramers per cross-section along the filament. Therefore, a central question for the structural biology of IFs is whether individual subunits can dissociate from assembled filaments and rebind at other sites. Using the fluorescently labeled IF-protein vimentin for assembly, we directly observe and quantitatively determine subunit exchange events between filaments as well as with soluble vimentin pools. Thereby we demonstrate that the cross-sectional polymorphism of donor and acceptor filaments plays an important role. We propose that in segments of donor filaments with more than the standard 32 molecules per cross-section, subunits are not as tightly bound and are predisposed to be released from the filament. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Navy-New Hampshire Wind Energy Program.

DTIC Science & Technology

1979-11-01

Hampshire 156 3.2.2.6.4 Legal/Institutional Barriers 157 3.2.2.6.4.1 Public Utilities Regulatory Policy Act ( PURPA ) 157 3.2.2.6.4.2 State of New...Regulatory Policy Act ( PURPA ) The greatest potential barrier to the introduction of wind turbine machines for the generation of electronic power is the...from qualified cogenerators at just and reasonable rates. Two of the provisions of PURPA are especially relc ant to the introduction of wind turbine

Self-assembly of nematic liquid crystal elastomer filaments

NASA Astrophysics Data System (ADS)

Wei, Wei-Shao; Xia, Yu; Yang, Shu; Yodh, A. G.

In this work we investigate the self-assembly of nematic liquid crystal polymer (NLCP) filaments and their corresponding cross-linked elastomer structures. Specifically, by fine-tuning surfactant concentration, prepolymer chain length, and temperature within a background aqueous phase we can generate filaments composed of oligomerized LC monomers. Filaments with narrowly dispersed diameters ranging from one hundred nanometers to a few micrometers can be obtained. Using polarization optical microscopy, we show that the nematic LCs within the filaments have an escaped radial structure. After photo-cross-linking, nematic liquid crystal elastomer filaments are obtained with well-maintained directors and smooth surface structure. Since these materials are elastomers, the size and mechanical and optical response of the filaments can be ''tuned'' near the nematic to isotropic phase transition temperature. This work is supported by NSF DMR16-07378, PENN MRSEC Grant DMR11-20901, and NASA Grant NNX08AO0G.

A Double-Sided Linear Primary Permanent Magnet Vernier Machine

PubMed Central

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

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.

Topology of interaction between titin and myosin thick filaments.

PubMed

Kellermayer, Miklós; Sziklai, Dominik; Papp, Zsombor; Decker, Brennan; Lakatos, Eszter; Mártonfalvi, Zsolt

2018-05-05

Titin is a giant protein spanning between the Z- and M-lines of the sarcomere. In the A-band titin is associated with the myosin thick filament. It has been speculated that titin may serve as a blueprint for thick-filament formation due to the super-repeat structure of its A-band domains. Accordingly, titin might provide a template that determines the length and structural periodicity of the thick filament. Here we tested the titin ruler hypothesis by mixing titin and myosin at in situ stoichiometric ratios (300 myosins per 12 titins) in buffers of different ionic strength (KCl concentration range 100-300 mM). The topology of the filamentous complexes was investigated with atomic force microscopy. We found that the samples contained distinct, segregated populations of titin molecules and myosin thick filaments. We were unable to identify complexes in which myosin molecules were regularly associated to either mono- or oligomeric titin in either relaxed or stretched states of the titin filaments. Thus, the electrostatically driven self-association is stronger in both myosin and titin than their binding to each other, and it is unlikely that titin functions as a geometrical template for thick-filament formation. However, when allowed to equilibrate configurationally, long myosin thick filaments appeared with titin oligomers attached to their surface. The titin meshwork formed on the thick-filament surface may play a role in controlling thick-filament length by regulating the structural dynamics of myosin molecules and placing a mechanical limit on the filament length. Copyright © 2018 Elsevier Inc. All rights reserved.

Physical principles of filamentous protein self-assembly kinetics

NASA Astrophysics Data System (ADS)

Michaels, Thomas C. T.; Liu, Lucie X.; Meisl, Georg; Knowles, Tuomas P. J.

2017-04-01

The polymerization of proteins and peptides into filamentous supramolecular structures is an elementary form of self-organization of key importance to the functioning biological systems, as in the case of actin biofilaments that compose the cellular cytoskeleton. Aberrant filamentous protein self-assembly, however, is associated with undesired effects and severe clinical disorders, such as Alzheimer’s and Parkinson’s diseases, which, at the molecular level, are associated with the formation of certain forms of filamentous protein aggregates known as amyloids. Moreover, due to their unique physicochemical properties, protein filaments are finding extensive applications as biomaterials for nanotechnology. With all these different factors at play, the field of filamentous protein self-assembly has experienced tremendous activity in recent years. A key question in this area has been to elucidate the microscopic mechanisms through which filamentous aggregates emerge from dispersed proteins with the goal of uncovering the underlying physical principles. With the latest developments in the mathematical modeling of protein aggregation kinetics as well as the improvement of the available experimental techniques it is now possible to tackle many of these complex systems and carry out detailed analyses of the underlying microscopic steps involved in protein filament formation. In this paper, we review some classical and modern kinetic theories of protein filament formation, highlighting their use as a general strategy for quantifying the molecular-level mechanisms and transition states involved in these processes.

Design and market considerations for axial flux superconducting electric machine design

NASA Astrophysics Data System (ADS)

Ainslie, M. D.; George, A.; Shaw, R.; Dawson, L.; Winfield, A.; Steketee, M.; Stockley, S.

2014-05-01

In this paper, the authors investigate a number of design and market considerations for an axial flux superconducting electric machine design that uses high temperature superconductors. The axial flux machine design is assumed to utilise high temperature superconductors in both wire (stator winding) and bulk (rotor field) forms, to operate over a temperature range of 65-77 K, and to have a power output in the range from 10s of kW up to 1 MW (typical for axial flux machines), with approximately 2-3 T as the peak trapped field in the bulk superconductors. The authors firstly investigate the applicability of this type of machine as a generator in small- and medium-sized wind turbines, including the current and forecasted market and pricing for conventional turbines. Next, a study is also carried out on the machine's applicability as an in-wheel hub motor for electric vehicles. Some recommendations for future applications are made based on the outcome of these two studies. Finally, the cost of YBCO-based superconducting (2G HTS) wire is analysed with respect to competing wire technologies and compared with current conventional material costs and current wire costs for both 1G and 2G HTS are still too great to be economically feasible for such superconducting devices.

Low-cost composite blades for the Mod-0A wind turbines

NASA Technical Reports Server (NTRS)

Weingart, O.

1982-01-01

Low cost approaches to the design and fabrication of blades for a two-bladed 200 kW wind turbine were identified and the applicability of the techniques to larger and smaller blades was assessed. Blade tooling was designed and fabricated. Two complete blades and a partial blade for tool tryout were built. The patented TFT process was used to wind the entire blade. This process allows rapid winding of an axially oriented composite onto a tapered mandrel, with tapered wall thickness. The blade consists of a TFT glass-epoxy airfoil structure filament wound onto a steel root end fitting. The fitting is, in turn, bolted to a conical steel adapter section to provide for mounting attachment to the hub. Structural analysis, blade properties, and cost and weight analysis are described.

Grumman Windstream 25 wind turbine generator. Final test report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sexton, J.H.

1980-03-01

The Grumman Windstream 25 Wind Turbine Generator (WTG) tested at the Rocky Flats Small Wind Systems Test Center (WSTC) was one of nineteen Windstream 25's manufactured by Grumman Energy Systems, Inc. The machine was considered a first generation prototype and is no longer being produced. While being tested at the WSTC, the Windstream 25 was still in a developmental stage, and operational problems were experienced during its testing period. It is important to underscore, however, that problems encountered during testing of the machine created valuable gains in experience and data for both Rocky Flats and Grumman personnel. It is believedmore » these gains have contributed significantly to further development of Grumman WTG's.« less

On the fragmentation of filaments in a molecular cloud simulation

NASA Astrophysics Data System (ADS)

Chira, R.-A.; Kainulainen, J.; Ibáñez-Mejía, J. C.; Henning, Th.; Mac Low, M.-M.

2018-03-01

Context. The fragmentation of filaments in molecular clouds has attracted a lot of attention recently as there seems to be a close relation between the evolution of filaments and star formation. The study of the fragmentation process has been motivated by simple analytical models. However, only a few comprehensive studies have analysed the evolution of filaments using numerical simulations where the filaments form self-consistently as part of large-scale molecular cloud evolution. Aim. We address the early evolution of parsec-scale filaments that form within individual clouds. In particular, we focus on three questions: How do the line masses of filaments evolve? How and when do the filaments fragment? How does the fragmentation relate to the line masses of the filaments? Methods: We examine three simulated molecular clouds formed in kiloparsec-scale numerical simulations performed with the FLASH adaptive mesh refinement magnetohydrodynamic code. The simulations model a self-gravitating, magnetised, stratified, supernova-driven interstellar medium, including photoelectric heating and radiative cooling. We follow the evolution of the clouds for 6 Myr from the time self-gravity starts to act. We identify filaments using the DisPerSe algorithm, and compare the results to other filament-finding algorithms. We determine the properties of the identified filaments and compare them with the predictions of analytic filament stability models. Results: The average line masses of the identified filaments, as well as the fraction of mass in filamentary structures, increases fairly continuously after the onset of self-gravity. The filaments show fragmentation starting relatively early: the first fragments appear when the line masses lie well below the critical line mass of Ostriker's isolated hydrostatic equilibrium solution ( 16 M⊙ pc-1), commonly used as a fragmentation criterion. The average line masses of filaments identified in three-dimensional volume density cubes

Design of a Modular E-Core Flux Concentrating Axial Flux Machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Sozer, Yilmaz; Husain, Iqbal

2015-09-02

In this paper a novel E-Core axial flux machine is proposed. The machine has a double stator-single rotor configuration with flux concentrating ferrite magnets, and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single phase and a three-phase version of the E-Core machine. Case study for a 1.1 kW, 400 rpm machine for both the single phase and three-phase axial flux machine is presented. The results are verifiedmore » through 3D finite element analysis.« less

Flux Cancellation Leading to Solar Filament Eruptions

NASA Astrophysics Data System (ADS)

Popescu, R. M.; Panesar, N. K.; Sterling, A. C.; Moore, R. L.

2016-12-01

Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to 100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable by either magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both onboard the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions and find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two events in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field and are in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

Flux Cancellation Leading to CME Filament Eruptions

NASA Technical Reports Server (NTRS)

Popescu, Roxana M.; Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

Solar filaments are strands of relatively cool, dense plasma magnetically suspended in the lower density hotter solar corona. They trace magnetic polarity inversion lines (PILs) in the photosphere below, and are supported against gravity at heights of up to approx.100 Mm above the chromosphere by the magnetic field in and around them. This field erupts when it is rendered unstable, often by magnetic flux cancellation or emergence at or near the PIL. We have studied the evolution of photospheric magnetic flux leading to ten observed filament eruptions. Specifically, we look for gradual magnetic changes in the neighborhood of the PIL prior to and during eruption. We use Extreme Ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA), and magnetograms from the Helioseismic and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO), to study filament eruptions and their photospheric magnetic fields. We examine whether flux cancellation or/and emergence leads to filament eruptions. We find that continuous flux cancellation was present at the PIL for many hours prior to each eruption. We present two CME-producing eruptions in detail and find the following: (a) the pre-eruption filament-holding core field is highly sheared and appears in the shape of a sigmoid above the PIL; (b) at the start of the eruption the opposite arms of the sigmoid reconnect in the middle above the site of (tether-cutting) flux cancellation at the PIL; (c) the filaments first show a slow-rise, followed by a fast-rise as they erupt. We conclude that these two filament eruptions result from flux cancellation in the middle of the sheared field, and thereafter evolve in agreement with the standard model for a CME/flare filament eruption from a closed bipolar magnetic field [flux cancellation (van Ballegooijen and Martens 1989 and Moore and Roumelrotis 1992) and runaway tether-cutting (Moore et. al 2001)].

Cofilin-Linked Changes in Actin Filament Flexibility Promote Severing

PubMed Central

McCullough, Brannon R.; Grintsevich, Elena E.; Chen, Christine K.; Kang, Hyeran; Hutchison, Alan L.; Henn, Arnon; Cao, Wenxiang; Suarez, Cristian; Martiel, Jean-Louis; Blanchoin, Laurent; Reisler, Emil; De La Cruz, Enrique M.

2011-01-01

The actin regulatory protein, cofilin, increases the bending and twisting elasticity of actin filaments and severs them. It has been proposed that filaments partially decorated with cofilin accumulate stress from thermally driven shape fluctuations at bare (stiff) and decorated (compliant) boundaries, thereby promoting severing. This mechanics-based severing model predicts that changes in actin filament compliance due to cofilin binding affect severing activity. Here, we test this prediction by evaluating how the severing activities of vertebrate and yeast cofilactin scale with the flexural rigidities determined from analysis of shape fluctuations. Yeast actin filaments are more compliant in bending than vertebrate actin filaments. Severing activities of cofilactin isoforms correlate with changes in filament flexibility. Vertebrate cofilin binds but does not increase the yeast actin filament flexibility, and does not sever them. Imaging of filament thermal fluctuations reveals that severing events are associated with local bending and fragmentation when deformations attain a critical angle. The critical severing angle at boundaries between bare and cofilin-decorated segments is smaller than in bare or fully decorated filaments. These measurements support a cofilin-severing mechanism in which mechanical asymmetry promotes local stress accumulation and fragmentation at boundaries of bare and cofilin-decorated segments, analogous to failure of some nonprotein materials. PMID:21723825

Optical spectroscopy using gas-phase femtosecond laser filamentation.

PubMed

Odhner, Johanan; Levis, Robert

2014-01-01

Femtosecond laser filamentation occurs as a dynamic balance between the self-focusing and plasma defocusing of a laser pulse to produce ultrashort radiation as brief as a few optical cycles. This unique source has many properties that make it attractive as a nonlinear optical tool for spectroscopy, such as propagation at high intensities over extended distances, self-shortening, white-light generation, and the formation of an underdense plasma. The plasma channel that constitutes a single filament and whose position in space can be controlled by its input parameters can span meters-long distances, whereas multifilamentation of a laser beam can be sustained up to hundreds of meters in the atmosphere. In this review, we briefly summarize the current understanding and use of laser filaments for spectroscopic investigations of molecules. A theoretical framework of filamentation is presented, along with recent experimental evidence supporting the established understanding of filamentation. Investigations carried out on vibrational and rotational spectroscopy, filament-induced breakdown, fluorescence spectroscopy, and backward lasing are discussed.

Disc-geometry homopolar synchronous machine

NASA Astrophysics Data System (ADS)

Evans, P. D.; Eastham, J. F.

1980-09-01

Results of an experimental and theoretical investigation of a disc-geometry homopolar synchronous machine with field excitation on the primary side are presented. The unlaminated mild-steel rotor contains no windings and is brushless. The prototype machine produces approximately 7.5 kW of mechanical output at 3000 rev/min, with a product of power factor and efficiency greater than 0.7. The construction of the stator core is unusual and incorporates both laminated and unlaminated portions. The magnetic circuit is also arranged to minimize the axial force between the stator and rotor. A novel rotor design which achieves a reduced quadrature-axis reactance is shown experimentally to be superior to the conventional homopolar rotor.

Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

NASA Technical Reports Server (NTRS)

Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L.

2010-01-01

It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

Wind - Prototypes on the landscape

NASA Astrophysics Data System (ADS)

Smith, M. L.

1981-12-01

Large wind turbines are shown to be attractive to utilities because of the potential for decreasing gas and oil consumption, the relatively low costs for entry into the field, and the wide distribution of wind energy. The total generating capacity can be increased in incremental steps, experience in construction and operation of large turbines have been gained from the NASA Mod O, OA, 1, and 2 models, and advances in manufacturing processes will make the large turbines competitive as replacement power for oil and gas burning utility generators. The 300 ft rotor Mod 2 machines are described, along with designs for the Mod 5A and Mod 5B wind turbines, with 400 and 422 ft, 6.2 and 7.2 MW rotors and outputs, respectively. Current plans for multi-MW windfarms are reviewed, and the option of using the land around large wind turbines for other purposes is stressed.

Formation of a solar Hα filament from orphan penumbrae

NASA Astrophysics Data System (ADS)

Buehler, D.; Lagg, A.; van Noort, M.; Solanki, S. K.

2016-05-01

Aims: The formation and evolution of an Hα filament in active region (AR) 10953 is described. Methods: Observations from the Solar Optical Telescope (SOT) aboard the Hinode satellite starting from UT 18:09 on 27th April 2007 until UT 06:08 on 1st May 2007 were analysed. 20 scans of the 6302 Å Fe I line pair recorded by SOT/SP were inverted using the spatially coupled version of the SPINOR code. The inversions were analysed together with co-spatial SOT/BFI G-band and Ca II H and SOT/NFI Hα observations. Results: Following the disappearance of an initial Hα filament aligned along the polarity inversion line (PIL) of the AR, a new Hα filament formed in its place some 20 h later, which remained stable for, at least, another 1.5 days. The creation of the new Hα filament was driven by the ascent of horizontal magnetic fields from the photosphere into the chromosphere at three separate locations along the PIL. The magnetic fields at two of these locations were situated directly underneath the initial Hα filament and formed orphan penumbrae already aligned along the Hα filament channel. The 700 G orphan penumbrae were stable and trapped in the photosphere until the disappearance of the overlying initial Hα filament, after which they started to ascend into the chromosphere at 10 ± 5 m/s. Each ascent was associated with a simultaneous magnetic flux reduction of up to 50% in the photosphere. The ascended orphan penumbrae formed dark seed structures in Hα in parallel with the PIL, which elongated and merged to form an Hα filament. The filament channel featured horizontal magnetic fields of on average 260 G at log (τ) = -2 suspended above the nearly field-free lower photosphere. The fields took on an overall inverse configuration at log (τ) = -2 suggesting a flux rope topology for the new Hα filament. The destruction of the initial Hα filament was likely caused by the flux emergence at the third location along the PIL. Conclusions: We present a new

Importance of filament diameter when using bass brushing technique.

PubMed

Vowles, A D; Wade, A B

1977-08-01

A comparative study using a crossover experimental construction was made of the effectiveness of brushes containing 6/10 nylon filaments of 0.132 mm mean diameter using a Bass technique with those containing filaments of the same type of nylon but 0.280 mm diameter. Each type of brush was used for a 2-week period. Even though the finer filament brushes contained more than three times as many filaments, they were inferior in cleaning achievement to the brushes with the broader filaments. The difference was particularly marked on the facial aspect, but was largely nullified lingually. The effectiveness of the Bass technique in the gingival zone demonstrated in a previous investigation when brushes containing filaments of 0.18 and 0.20 mm were used, was not found in this investigation. It is concluded that filament diameter is critical in achieving effective cleaning using the Bass technique.

Beam wandering of femtosecond laser filament in air.

PubMed

Yang, Jing; Zeng, Tao; Lin, Lie; Liu, Weiwei

2015-10-05

The spatial wandering of a femtosecond laser filament caused by the filament heating effect in air has been studied. An empirical formula has also been derived from the classical Karman turbulence model, which determines quantitatively the displacement of the beam center as a function of the propagation distance and the effective turbulence structure constant. After fitting the experimental data with this formula, the effective turbulence structure constant has been estimated for a single filament generated in laboratory environment. With this result, one may be able to estimate quantitatively the displacement of a filament over long distance propagation and interpret the practical performance of the experiments assisted by femtosecond laser filamentation, such as remote air lasing, pulse compression, high order harmonic generation (HHG), etc.

Scroll wave filaments self-wrap around unexcitable heterogeneities.

PubMed

Jiménez, Zulma A; Steinbock, Oliver

2012-09-01

Scroll waves are three-dimensional excitation vortices rotating around one-dimensional phase singularities called filaments. In experiments with a chemical reaction-diffusion system and in numerical simulations, we study the pinning of closed filament loops to inert cylindrical heterogeneities. We show that the filament wraps itself around the heterogeneity and thus avoids contraction and annihilation. This entwining steadily increases the total length of the pinned filament and reshapes the entire rotation backbone of the vortex. Self-pinning is fastest for thin cylinders with radii not much larger than the core of the unpinned rotor. The process ends when the filament is attached to the entire length of the cylinder. The possible importance of self-pinning in cardiac systems is discussed.

Dimensional quantization effects in the thermodynamics of conductive filaments

NASA Astrophysics Data System (ADS)

Niraula, D.; Grice, C. R.; Karpov, V. G.

2018-06-01

We consider the physical effects of dimensional quantization in conductive filaments that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin filament acquires a positive charge. Several applications of this finding include the host material polarization, the stability of filament constrictions, the equilibrium filament radius, polarity in device switching, and quantization of conductance.

Dimensional quantization effects in the thermodynamics of conductive filaments.

PubMed

Niraula, D; Grice, C R; Karpov, V G

2018-06-29

We consider the physical effects of dimensional quantization in conductive filaments that underlie operations of some modern electronic devices. We show that, as a result of quantization, a sufficiently thin filament acquires a positive charge. Several applications of this finding include the host material polarization, the stability of filament constrictions, the equilibrium filament radius, polarity in device switching, and quantization of conductance.

Propagation distance-resolved characteristics of filament-induced copper plasma

DOE PAGES

Ghebregziabher, Isaac; Hartig, Kyle C.; Jovanovic, Igor

2016-03-02

Copper plasma generated at different filament-copper interaction points was characterized by spectroscopic, acoustic, and imaging measurements. The longitudinal variation of the filament intensity was qualitatively determined by acoustic measurements in air. The maximum plasma temperature was measured at the location of peak filament intensity, corresponding to the maximum mean electron energy during plasma formation. The highest copper plasma density was measured past the location of the maximum electron density in the filament, where spectral broadening of the filament leads to enhanced ionization. Acoustic measurements in air and on solid target were correlated to reconstructed plasma properties. Lastly, optimal line emissionmore » is measured near the geometric focus of the lens used to produce the filament.« less

Installation and checkout of the DOE/NASA Mod-1 2000-kW wind turbine generator

NASA Technical Reports Server (NTRS)

Puthoff, R. L.; Collins, J. L.; Wolf, R. A.

1980-01-01

The paper describes the DOE/NASA Mod-1 wind turbine generator, its assembly and testing, and its installation at Boone, North Carolina. The paper concludes with performance data taken during the initial tests conducted on the machine. The successful installation and initial operation of the Mod-1 wind turbine generator has had the following results: (1) megawatt-size wind turbines can be operated satisfactorily on utility grids; (2) the structural loads can be predicted by existing codes; (3) assembly of the machine on top of the tower presents no major problem; (4) large blades 100 ft long can be transported long distances and over mountain roads; and (5) operating experience and performance data will contribute substantially to the design of future low-cost wind turbines.

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

COMPLEX FLARE DYNAMICS INITIATED BY A FILAMENT–FILAMENT INTERACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Chunming; McAteer, R. T. James; Liu, Rui

2015-11-01

We report on an eruption involving a relatively rare filament–filament interaction on 2013 June 21, observed by SDO and STEREO-B. The two filaments were separated in height with a “double-decker” configuration. The eruption of the lower filament began simultaneously with a descent of the upper filament, resulting in a convergence and direct interaction of the two filaments. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper filament. The subsequent coalescence of the filaments drove a bright front ahead of the erupting structures. The whole process was associated withmore » a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics.« less

Spatial evolution of laser filaments in turbulent air

NASA Astrophysics Data System (ADS)

Zeng, Tao; Zhu, Shiping; Zhou, Shengling; He, Yan

2018-04-01

In this study, the spatial evolution properties of laser filament clusters in turbulent air were evaluated using numerical simulations. Various statistical parameters were calculated, such as the percolation probability, filling factor, and average cluster size. The results indicate that turbulence-induced multi-filamentation can be described as a new phase transition universality class. In addition, during this process, the relationship between the average cluster size and filling factor could be fit by a power function. Our results are valuable for applications involving filamentation that can be influenced by the geometrical features of multiple filaments.

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.

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

Bundling of elastic filaments induced by hydrodynamic interactions

NASA Astrophysics Data System (ADS)

Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

2017-12-01

Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long

Energetics and kinetics of cooperative cofilin-actin filament interactions.

PubMed

Cao, Wenxiang; Goodarzi, Jim P; De La Cruz, Enrique M

2006-08-11

We have evaluated the thermodynamic parameters associated with cooperative cofilin binding to actin filaments, accounting for contributions of ion-linked equilibria, and determined the kinetic basis of cooperative cofilin binding. Ions weaken non-contiguous (isolated, non-cooperative) cofilin binding to an actin filament without affecting cooperative filament interactions. Non-contiguous cofilin binding is coupled to the dissociation of approximately 1.7 thermodynamically bound counterions. Counterion dissociation contributes approximately 40% of the total cofilin binding free energy (in the presence of 50 mM KCl). The non-contiguous and cooperative binding free energies are driven entirely by large, positive entropy changes, consistent with a cofilin-mediated increase in actin filament structural dynamics. The rate constant for cofilin binding to an isolated site on an actin filament is slow and likely to be limited by filament breathing. Cooperative cofilin binding arises from an approximately tenfold more rapid association rate constant and an approximately twofold slower dissociation rate constant. The more rapid association rate constant is presumably a consequence of cofilin-dependent changes in the average orientation of subdomain 2, subunit angular disorder and filament twist, which increase the accessibility of a neighboring cofilin-binding site on an actin filament. Cooperative association is more rapid than binding to an isolated site, but still slow for a second-order reaction, suggesting that cooperative binding is limited also by binding site accessibility. We suggest that the dissociation of actin-associated ions weakens intersubunit interactions in the actin filament lattice that enhance cofilin-binding site accessibility, favor cooperative binding and promote filament severing.

Large scale filaments associated with Milky Way spiral arms

NASA Astrophysics Data System (ADS)

Wang, Ke; Testi, Leonardo; Ginsburg, Adam; Walmsley, Malcolm; Molinari, Sergio; Schisano, Eugenio

2015-08-01

The ubiquity of filamentary structure at various scales through out 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 data complemented by spectral line cubes. We present a sample of the 9 most prominent Herschel filaments from a pilot search field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)×104 Msun, and beam-averaged (28", or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)x1022 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 due to local star formation activities. 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 scale height and therefore are not simply part of a grander turbulent cascade. These giant filaments, which often contain regularly spaced pc-scale clumps, are much larger than the filaments found in the Herschel Gould's Belt Survey, and they form the upper ends in the filamentary hierarchy. Full operational ALMA and NOEMA will be able to resolve and characterize similar filaments in nearby spiral galaxies, allowing us to compare the star formation in a uniform context of spiral arms.

Hanging Filament

NASA Image and Video Library

2014-06-16

The Sun sported a very long filament that stretched out over 500,000 miles (800,000 km) and was visible for several days (June 3-4, 2014). It broke apart and dissipated soon after the end of the video clip. Filaments are tenuous strands of plasma held above the Sun's surface by magnetic forces. They appear darker because their temperature is somewhat cooler than that of the Sun's surface. The still image, shown in a combination of two wavelengths of extreme ultraviolet light, was taken at 11:33 UT on June 4. Credit: NASA/Goddard/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Geometrical and Mechanical Properties Control Actin Filament Organization

PubMed Central

Ennomani, Hajer; Théry, Manuel; Nedelec, Francois; Blanchoin, Laurent

2015-01-01

The different actin structures governing eukaryotic cell shape and movement are not only determined by the properties of the actin filaments and associated proteins, but also by geometrical constraints. We recently demonstrated that limiting nucleation to specific regions was sufficient to obtain actin networks with different organization. To further investigate how spatially constrained actin nucleation determines the emergent actin organization, we performed detailed simulations of the actin filament system using Cytosim. We first calibrated the steric interaction between filaments, by matching, in simulations and experiments, the bundled actin organization observed with a rectangular bar of nucleating factor. We then studied the overall organization of actin filaments generated by more complex pattern geometries used experimentally. We found that the fraction of parallel versus antiparallel bundles is determined by the mechanical properties of actin filament or bundles and the efficiency of nucleation. Thus nucleation geometry, actin filaments local interactions, bundle rigidity, and nucleation efficiency are the key parameters controlling the emergent actin architecture. We finally simulated more complex nucleation patterns and performed the corresponding experiments to confirm the predictive capabilities of the model. PMID:26016478

Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin Filament Bundles in the Cytoskeleton Is Independent of Actin Filament Kinetics.

PubMed

Appaduray, Mark A; Masedunskas, Andrius; Bryce, Nicole S; Lucas, Christine A; Warren, Sean C; Timpson, Paul; Stear, Jeffrey H; Gunning, Peter W; Hardeman, Edna C

2016-01-01

The actin cytoskeleton is a dynamic network of filaments that is involved in virtually every cellular process. Most actin filaments in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin filament is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during filament assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin filament bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin filament bundles largely independent of the assembly and turnover of actin.

Analytical calculation of vibrations of electromagnetic origin in electrical machines

NASA Astrophysics Data System (ADS)

McCloskey, Alex; Arrasate, Xabier; Hernández, Xabier; Gómez, Iratxo; Almandoz, Gaizka

2018-01-01

Electrical motors are widely used and are often required to satisfy comfort specifications. Thus, vibration response estimations are necessary to reach optimum machine designs. This work presents an improved analytical model to calculate vibration response of an electrical machine. The stator and windings are modelled as a double circular cylindrical shell. As the stator is a laminated structure, orthotropic properties are applied to it. The values of those material properties are calculated according to the characteristics of the motor and the known material properties taken from previous works. Therefore, the model proposed takes into account the axial direction, so that length is considered, and also the contribution of windings, which differs from one machine to another. These aspects make the model valuable for a wide range of electrical motor types. In order to validate the analytical calculation, natural frequencies are calculated and compared to those obtained by Finite Element Method (FEM), giving relative errors below 10% for several circumferential and axial mode order combinations. It is also validated the analytical vibration calculation with acceleration measurements in a real machine. The comparison shows good agreement for the proposed model, being the most important frequency components in the same magnitude order. A simplified two dimensional model is also applied and the results obtained are not so satisfactory.

Design and analysis of linear fault-tolerant permanent-magnet vernier machines.

PubMed

Xu, Liang; Ji, Jinghua; Liu, Guohai; Du, Yi; Liu, Hu

2014-01-01

This paper proposes a new linear fault-tolerant permanent-magnet (PM) vernier (LFTPMV) machine, which can offer high thrust by using the magnetic gear effect. Both PMs and windings of the proposed machine are on short mover, while the long stator is only manufactured from iron. Hence, the proposed machine is very suitable for long stroke system applications. The key of this machine is that the magnetizer splits the two movers with modular and complementary structures. Hence, the proposed machine offers improved symmetrical and sinusoidal back electromotive force waveform and reduced detent force. Furthermore, owing to the complementary structure, the proposed machine possesses favorable fault-tolerant capability, namely, independent phases. In particular, differing from the existing fault-tolerant machines, the proposed machine offers fault tolerance without sacrificing thrust density. This is because neither fault-tolerant teeth nor the flux-barriers are adopted. The electromagnetic characteristics of the proposed machine are analyzed using the time-stepping finite-element method, which verifies the effectiveness of the theoretical analysis.

Mechanical model for filament buckling and growth by phase ordering.

PubMed

Rey, Alejandro D; Abukhdeir, Nasser M

2008-02-05

A mechanical model of open filament shape and growth driven by phase ordering is formulated. For a given phase-ordering driving force, the model output is the filament shape evolution and the filament end-point kinematics. The linearized model for the slope of the filament is the Cahn-Hilliard model of spinodal decomposition, where the buckling corresponds to concentration fluctuations. Two modes are predicted: (i) sequential growth and buckling and (ii) simultaneous buckling and growth. The relation among the maximum buckling rate, filament tension, and matrix viscosity is given. These results contribute to ongoing work in smectic A filament buckling.

Kinetic analysis of F-actin depolymerization in polymorphonuclear leukocyte lysates indicates that chemoattractant stimulation increases actin filament number without altering the filament length distribution

PubMed Central

1991-01-01

The rate of filamentous actin (F-actin) depolymerization is proportional to the number of filaments depolarizing and changes in the rate are proportional to changes in filament number. To determine the number and length of actin filaments in polymorphonuclear leukocytes and the change in filament number and length that occurs during the increase in F-actin upon chemoattractant stimulation, the time course of cellular F-actin depolymerization in lysates of control and peptide- stimulated cells was examined. F-actin was quantified by the TRITC- labeled phalloidin staining of pelletable actin. Lysis in 1.2 M KCl and 10 microM DNase I minimized the effects of F-actin binding proteins and G-actin, respectively, on the kinetics of depolymerization. To determine filament number and length from a depolymerization time course, depolymerization kinetics must be limited by the actin monomer dissociation rate. Comparison of time courses of depolymerization in the presence (pointed ends free) or absence (barbed and pointed ends free) of cytochalasin suggested depolymerization occurred from both ends of the filament and that monomer dissociation was rate limiting. Control cells had 1.7 +/- 0.4 x 10(5) filaments with an average length of 0.29 +/- 0.09 microns. Chemo-attractant stimulation for 90 s at room temperature with 0.02 microM N-formylnorleucylleucylphenylalanine caused a twofold increase in F-actin and about a two-fold increase in the total number of actin filaments to 4.0 +/- 0.5 x 10(5) filaments with an average length of 0.27 +/- 0.07 microns. In both cases, most (approximately 80%) of the filaments were quite short (less than or equal to 0.18 micron). The length distributions of actin filaments in stimulated and control cells were similar. PMID:1918158

Disintegration of an eruptive filament via interactions with quasi-separatrix layers

NASA Astrophysics Data System (ADS)

Liu, Rui; Chen, Jun; Wang, YuMing

2018-06-01

The disintegration of solar filaments via mass drainage is a frequently observed phenomenon during a variety of filament activities. It is generally considered that the draining of dense filament material is directed by both gravity and magnetic field, yet the detailed process remains elusive. Here we report on a partial filament eruption during which filament material drains downward to the surface not only along the filament's legs, but to a remote flare ribbon through a fan-out curtain-like structure. It is found that the magnetic configuration is characterized by two conjoining dome-like quasi-sepratrix layers (QSLs). The filament is located underneath one QSL dome, whose footprint apparently bounds the major flare ribbons resulting from the filament eruption, whereas the remote flare ribbon matches well with the other QSL dome's far-side footprint. We suggest that the interaction of the filament with the overlying QSLs results in the splitting and disintegration of the filament.

System Applies Polymer Powder To Filament Tow

NASA Technical Reports Server (NTRS)

Baucom, Robert M.; Snoha, John J.; Marchello, Joseph M.

1993-01-01

Polymer powder applied uniformly and in continuous manner. Powder-coating system applies dry polymer powder to continuous fiber tow. Unique filament-spreading technique, combined with precise control of tension on fibers in system, ensures uniform application of polymer powder to web of spread filaments. Fiber tows impregnated with dry polymer powders ("towpregs") produced for preform-weaving and composite-material-molding applications. System and process valuable to prepreg industry, for production of flexible filament-windable tows and high-temperature polymer prepregs.

A Robust Actin Filaments Image Analysis Framework

PubMed Central

Alioscha-Perez, Mitchel; Benadiba, Carine; Goossens, Katty; Kasas, Sandor; Dietler, Giovanni; Willaert, Ronnie; Sahli, Hichem

2016-01-01

The cytoskeleton is a highly dynamical protein network that plays a central role in numerous cellular physiological processes, and is traditionally divided into three components according to its chemical composition, i.e. actin, tubulin and intermediate filament cytoskeletons. Understanding the cytoskeleton dynamics is of prime importance to unveil mechanisms involved in cell adaptation to any stress type. Fluorescence imaging of cytoskeleton structures allows analyzing the impact of mechanical stimulation in the cytoskeleton, but it also imposes additional challenges in the image processing stage, such as the presence of imaging-related artifacts and heavy blurring introduced by (high-throughput) automated scans. However, although there exists a considerable number of image-based analytical tools to address the image processing and analysis, most of them are unfit to cope with the aforementioned challenges. Filamentous structures in images can be considered as a piecewise composition of quasi-straight segments (at least in some finer or coarser scale). Based on this observation, we propose a three-steps actin filaments extraction methodology: (i) first the input image is decomposed into a ‘cartoon’ part corresponding to the filament structures in the image, and a noise/texture part, (ii) on the ‘cartoon’ image, we apply a multi-scale line detector coupled with a (iii) quasi-straight filaments merging algorithm for fiber extraction. The proposed robust actin filaments image analysis framework allows extracting individual filaments in the presence of noise, artifacts and heavy blurring. Moreover, it provides numerous parameters such as filaments orientation, position and length, useful for further analysis. Cell image decomposition is relatively under-exploited in biological images processing, and our study shows the benefits it provides when addressing such tasks. Experimental validation was conducted using publicly available datasets, and in osteoblasts

Safety assessment of continuous glass filaments used in eclipse.

PubMed

Swauger, J E; Foy, J W

2000-11-01

Eclipse is a cigarette that produces smoke by primarily heating, rather than burning, tobacco. The Eclipse heat source assembly employs a continuous filament glass mat jacket to insulate the heat source. The glass mat insulator is composed of continuous glass filaments and a binder. The purpose of this article is to address the potential toxicological significance of the continuous glass filaments under the conditions of intended use. Transfer data and the unique physical characteristics of the filaments demonstrate that significant exposure of the smoker will not occur. The available environmental survey data clearly demonstrate that Eclipse smokers are extremely unlikely to be exposed to continuous glass filaments at a level that represents a biologically significant increase over background exposure to glass fibers. The chemical composition of the continuous glass filaments used in Eclipse is generally similar to C-glass fiber compositions such as MMVF 11 that have failed to produce either tumors or fibrosis in chronic inhalation studies conducted in rats. In vitro dissolution data demonstrate that the continuous glass filaments used in Eclipse are more soluble than biologically active fibers such as rock wool (MMVF 21) or asbestos. However, the continuous glass filaments used in Eclipse were not as soluble in simulated extracellular lung fluid as representative C-glass fibers (MMVF 10 and MMVF 11). In brief, exposure of Eclipse smokers to continuous glass filaments is extremely unlikely to occur at a level that may be construed to be of biological significance.

Wind turbines for electric utilities: Development status and economics

NASA Technical Reports Server (NTRS)

Ramler, J. R.; Donovan, R. M.

1979-01-01

The technology and economics of the large, horizontal-axis wind turbines currently in the Federal Wind Energy Program are presented. Wind turbine technology advancements made in the last several years are discussed. It is shown that, based on current projections of the costs of these machines when produced in quantity, they should be attractive for utility application. The cost of electricity (COE) produced at the busbar is shown to be a strong function of the mean wind speed at the installation site. The breakeven COE as a fuel saver is discussed and the COE range that would be generally attractive to utilities is indicated.

Wind turbines for electric utilities - Development status and economics

NASA Technical Reports Server (NTRS)

Ramler, J. R.; Donovan, R. M.

1979-01-01

The technology and economics of the large, horizontal-axis wind turbines currently in the Federal Wind Energy Program are presented. Wind turbine technology advancements made in the last several years are discussed. It is shown that, based on current projections of the costs of these machines when produced in quantity, they should be attractive for utility application. The cost of electricity (COE) produced at the busbar is shown to be a strong function of the mean wind speed at the installation site. The breakeven COE as a 'fuel saver' is discussed and the COE range that would be generally attractive to utilities is indicated.

Two-dimensional photoacoustic imaging of femtosecond filament in water

NASA Astrophysics Data System (ADS)

Potemkin, F. V.; Mareev, E. I.; Rumiantsev, B. V.; Bychkov, A. S.; Karabutov, A. A.; Cherepetskaya, E. B.; Makarov, V. A.

2018-07-01

We report a first-of-its-kind optoacoustic tomography of a femtosecond filament in water. Using a broadband (~100 MHz) piezoelectric transducer and a back-projection reconstruction technique, a single filament profile was retrieved. Obtained pressure distribution induced by the femtosecond filament allowed us to identify the size of the core and the energy reservoir with spatial resolution better than 10 µm. The photoacoustic imaging provides direct measurements of the energy deposition into the medium under filamentation of ultrashort laser pulses that cannot be obtained by existing techniques. In combination with a relative simplicity and high accuracy, photoacoustic imaging can be considered as a breakthrough instrument for filamentation investigation.

Grumman WS33 wind system: prototype construction and testing, Phase II technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adler, F.M.; Henton, P.; King, P.W.

1980-11-01

The prototype fabrication and testing of the 8 kW small wind energy conversion system are reported. The turbine is a three-bladed, down-wind machine designed to interface directly with an electrical utility network. The machine as finally fabricated is rated at 15 kW at 24 mpH and peak power of 18 kW at 35 mph. Utility compatible electrical power is generated in winds between a cut-in speed of 9 mph and a cut-out speed of 35 mph by using the torque characteristics of the unit's induction generator combined with the rotor aerodynamics to maintain essentially constant speed. Inspection procedures, pre-delivery testing,more » and a cost analysis are included.« less

Thioredoxin is required for filamentous phage assembly.

PubMed Central

Russel, M; Model, P

1985-01-01

Sequence comparisons show that the fip gene product of Escherichia coli, which is required for filamentous phage assembly, is thioredoxin. Thioredoxin serves as a cofactor for reductive processes in many cell types and is a constituent of phage T7 DNA polymerase. The fip-1 mutation makes filamentous phage and T7 growth temperature sensitive in cells that carry it. The lesion lies within a highly conserved thioredoxin active site. Thioredoxin reductase (NADPH), as well as thioredoxin, is required for efficient filamentous phage production. Mutant phages defective in phage gene I are particularly sensitive to perturbations in the fip-thioredoxin system. A speculative model is presented in which thioredoxin reductase, thioredoxin, and the gene I protein interact to drive an engine for filamentous phage assembly. Images PMID:3881756

Electric converters of electromagnetic strike machine with capacitor supply

NASA Astrophysics Data System (ADS)

Usanov, K. M.; Volgin, A. V.; Kargin, V. A.; Moiseev, A. P.; Chetverikov, E. A.

2018-03-01

The application of pulse linear electromagnetic engines in small power strike machines (energy impact is 0.01...1.0 kJ), where the characteristic mode of rare beats (pulse seismic vibrator, the arch crash device bins bulk materials), is quite effective. At the same time, the technical and economic performance of such machines is largely determined by the ability of the power source to provide a large instantaneous power of the supply pulses in the winding of the linear electromagnetic motor. The use of intermediate energy storage devices in power systems of rare-shock LEME makes it possible to obtain easily large instantaneous powers, forced energy conversion, and increase the performance of the machine. A capacitor power supply of a pulsed source of seismic waves is proposed for the exploration of shallow depths. The sections of the capacitor storage (CS) are connected to the winding of the linear electromagnetic motor by thyristor dischargers, the sequence of activation of which is determined by the control device. The charge of the capacitors to the required voltage is made directly from the battery source, or through the converter from a battery source with a smaller number of batteries.

Simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament induced by a single shock wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yuandeng; Liu, Ying D.; Chen, P. F.

2014-11-10

We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament launched by a single shock wave. Using Hα Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the filaments showsmore » weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the filament and the weakening (due to reflection) of the shock wave before the interaction. Large-amplitude longitudinal oscillation is observed in the other filament after the passing of the shock wave. The velocity amplitude and period are about 26.8 km s{sup –1} and 80.3 minutes, respectively. We propose that the orientation of a filament or prominence relative to the normal vector of the incoming shock should be an important factor for launching transverse or longitudinal filament oscillations. In addition, the restoring forces of the transverse prominence are most likely due to the coupling of gravity and magnetic tension of the supporting magnetic field, while that for the longitudinal filament oscillation is probably the resultant force of gravity and magnetic pressure.« less

Long-range self-organization of cytoskeletal myosin II filament stacks.

PubMed

Hu, Shiqiong; Dasbiswas, Kinjal; Guo, Zhenhuan; Tee, Yee-Han; Thiagarajan, Visalatchi; Hersen, Pascal; Chew, Teng-Leong; Safran, Samuel A; Zaidel-Bar, Ronen; Bershadsky, Alexander D

2017-02-01

Although myosin II filaments are known to exist in non-muscle cells, their dynamics and organization are incompletely understood. Here, we combined structured illumination microscopy with pharmacological and genetic perturbations, to study the process of actomyosin cytoskeleton self-organization into arcs and stress fibres. A striking feature of the myosin II filament organization was their 'registered' alignment into stacks, spanning up to several micrometres in the direction orthogonal to the parallel actin bundles. While turnover of individual myosin II filaments was fast (characteristic half-life time 60 s) and independent of actin filament turnover, the process of stack formation lasted a longer time (in the range of several minutes) and required myosin II contractility, as well as actin filament assembly/disassembly and crosslinking (dependent on formin Fmnl3, cofilin1 and α-actinin-4). Furthermore, myosin filament stack formation involved long-range movements of individual myosin filaments towards each other suggesting the existence of attractive forces between myosin II filaments. These forces, possibly transmitted via mechanical deformations of the intervening actin filament network, may in turn remodel the actomyosin cytoskeleton and drive its self-organization.

Filaments in Lupus I

NASA Astrophysics Data System (ADS)

Takahashi, Satoko; Rodon, J.; De Gregorio-Monsalvo, I.; Plunkett, A.

2017-06-01

The mechanisms behind the formation of sub-stellar mass sources are key to determine the populations at the low-mass end of the stellar distribution. Here, we present mapping observations toward the Lupus I cloud in C18O(2-1) and 13CO(2-1) obtained with APEX. We have identified a few velocity-coherent filaments. Each contains several substellar mass sources that are also identified in the 1.1mm continuum data (see also SOLA catalogue presentation). We will discuss the velocity structure, fragmentation properties of the identified filaments, and the nature of the detected sources.

Machine Learning Topological Invariants with Neural Networks

NASA Astrophysics Data System (ADS)

Zhang, Pengfei; Shen, Huitao; Zhai, Hui

2018-02-01

In this Letter we supervisedly train neural networks to distinguish different topological phases in the context of topological band insulators. After training with Hamiltonians of one-dimensional insulators with chiral symmetry, the neural network can predict their topological winding numbers with nearly 100% accuracy, even for Hamiltonians with larger winding numbers that are not included in the training data. These results show a remarkable success that the neural network can capture the global and nonlinear topological features of quantum phases from local inputs. By opening up the neural network, we confirm that the network does learn the discrete version of the winding number formula. We also make a couple of remarks regarding the role of the symmetry and the opposite effect of regularization techniques when applying machine learning to physical systems.

Observations of the Merging of Two Quiescent Filaments

NASA Astrophysics Data System (ADS)

Mikurda, Katarzyna; Martin, S. F.

2007-05-01

The two filaments were observed close to disk center in the same field of view of approximately 9x9 arc. min. The observations were made using a tunable lithium niobate, narrow band etalon on the 25 cm Martin Solar Telescope at Helio Research in southern California. One filament was close to the equator and was oriented nearly east-west and the other, to the west, was oriented north-south with the north end approximately 120 Mm from the west end of the equatorial filament. Continued observations were made of these filaments for 2 to 5.5 hours per day between October 10 and 15, 2004. The observations were made at multiple wavelengths within + and - 1 Å around Hα. We compared Hα centerline images with data taken by SOHO/EIT at 304A and observed significant differences in the evolution of the filaments at these wavelengths. For example, in EIT 304 Å images the two filaments seem to join on October 12, i.e. about two days earlier than in Hα. Moreover, the observed merging took longer (over three days) in Hα than in EIT 304 Å images, where it took place on a single day. The dynamics of the merger event is demonstrated with Hα and EIT 304 Å movies. The Doppler velocities calculated from the line wings images before, during and after the merging event were in the normal range for quiescent filaments. In our investigation of subsequent SOHO/EIT images at 304 Å we found no sign of an eruption due to the merging of the filaments. The contribution of KM was supported under NASA grant NAG5-10852 and SFM acknowledges NSF grant ATM-0519249.

Dynamics and Breakup of a Contracting Viscous Filament

NASA Astrophysics Data System (ADS)

Wilkes, Edward; Notz, Patrick; Ambravaneswaran, Bala; Basaran, Osman

1999-11-01

Free viscous filaments are formed during the breakup of liquid drops and jets. Such filaments are typically precursors of satellite droplets that are often undesirable in applications such as ink-jet printing. In this paper, the contraction of an axisymmetric liquid filament due to action of surface tension is studied theoretically. The analysis is based on solving (a) the full Navier-Stokes system in two-dimensions (2-d) and (b) a one-dimensional (1-d) approximation of the exact equations based on slender-jet theory. The rigorous, 2-d calculations are carried out with finite element algorithms using either algebraic or elliptic mesh generation. As the filament contracts, bulbous regions form at its two ends. When the initial aspect ratio a/b and/or the Reynolds number Re are sufficiently low, the ends coalesce into an oscillating free drop. Filament breakup occurs when a/b and/or Re are sufficiently high. The 2-d algorithms reveal for the first time that liquid filaments of finite viscosity can overturn prior to interface rupture. The power of elliptic mesh generation over algebraic methods in analyzing such situations is highlighted.

Oriented thick and thin filaments in Amoeba proteus.

PubMed

Rinaldi, R A; Hrebenda, B

1975-07-01

Actin and myosin filaments as a foundation of contractile systems are well established from ameba to man (3). Wolpert et al. (19) isolated by differential centrifugation from Amoeba proteus a motile fraction composed of filaments which moved upon the addition of ATP. Actin filaments are found in amebas (1, 12, 13) which react with vertebrate heavy meromyosin (HMM), forming arrowhead complexes as vertebrate actin (3, 9), and are prominent within the ectoplasmic tube where some of them are attached to the plasmalemma (1, 12). Thick and thin filaments possessing the morphological characteristics of myosin and actin have been obtained from isolated ameba cytoplasm (18, 19). In addition, there are filaments exhibiting ATPase activity in amebas which react with actin (12, 16, 17). However, giant ameba (Chaos-proteus) shapes are difficult to preserve, and the excellent contributions referred to above are limited by visible distortions occurring in the amebas (rounding up, pseudopods disappearing, and cellular organelles swelling) upon fixation. Achievement of normal ameboid shape in recent glycerination work (15) led us to attempt other electron microscope fixation techniques, resulting in a surprising preservation of A. proteus with a unique orientation of thick and thin filaments in the ectoplasmic region.

Accretion-driven turbulence in filaments - I. Non-gravitational accretion

NASA Astrophysics Data System (ADS)

Heigl, S.; Burkert, A.; Gritschneder, M.

2018-03-01

We study accretion-driven turbulence for different inflow velocities in star-forming filaments using the code RAMSES. Filaments are rarely isolated objects and their gravitational potential will lead to radially dominated accretion. In the non-gravitational case, accretion by itself can already provoke non-isotropic, radially dominated turbulent motions responsible for the complex structure and non-thermal line widths observed in filaments. We find that there is a direct linear relation between the absolute value of the total density-weighted velocity dispersion and the infall velocity. The turbulent velocity dispersion in the filaments is independent of sound speed or any net flow along the filament. We show that the density-weighted velocity dispersion acts as an additional pressure term, supporting the filament in hydrostatic equilibrium. Comparing to observations, we find that the projected non-thermal line width variation is generally subsonic independent of inflow velocity.

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.

Predicting Structural Behavior of Filament Wound Composite Pressure Vessel Using Three Dimensional Shell Analysis

NASA Astrophysics Data System (ADS)

Madhavi, M.; Venkat, R.

2014-01-01

Fiber reinforced polymer composite materials with their higher specific strength, moduli and tailorability characteristics will result in reduction of weight of the structure. The composite pressure vessels with integrated end domes develop hoop stresses that are twice longitudinal stresses and when isotropic materials like metals are used for development of the hardware and the material is not fully utilized in the longitudinal/meridional direction resulting in over weight components. The determination of a proper winding angles and thickness is very important to decrease manufacturing difficulties and to increase structural efficiency. In the present study a methodology is developed to understand structural characteristics of filament wound pressure vessels with integrated end domes. Progressive ply wise failure analysis of composite pressure vessel with geodesic end domes is carried out to determine matrix crack failure, burst pressure values at various positions of the shell. A three dimensional finite element analysis is computed to predict the deformations and stresses in the composite pressure vessel. The proposed method could save the time to design filament wound structures, to check whether the ply design is safe for the given input conditions and also can be adapted to non-geodesic structures. The results can be utilized to understand structural characteristics of filament wound pressure vessels with integrated end domes. This approach can be adopted for various applications like solid rocket motor casings, automobile fuel storage tanks and chemical storage tanks. Based on the predictions a composite pressure vessel is designed and developed. Hydraulic test is performed on the composite pressure vessel till the burst pressure.

The effect of delays on filament oscillations and stability

NASA Astrophysics Data System (ADS)

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

1998-11-01

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

A First Approach to Filament Dynamics

ERIC Educational Resources Information Center

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

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…

Scanning For Hotspots In Lamp Filaments

NASA Technical Reports Server (NTRS)

Powers, Charles E.; Van Sant, Tim; Leidecker, Henning

1993-01-01

Scanning photometer designed for use in investigation of failures of incandescent lamp filaments. Maps brightness as function of position along each filament to identify bright (hot) spots, occurring at notches and signifying incipient breaks or rewelds. Also used to measure nonuniformity in outputs of such linear devices as light-emitting diodes, and to measure diffraction patterns of lenses.

Magnetic Fields in the Massive Dense Cores of the DR21 Filament: Weakly Magnetized Cores in a Strongly Magnetized Filament

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ching, Tao-Chung; Lai, Shih-Ping; Zhang, Qizhou

We present Submillimeter Array 880 μ m dust polarization observations of six massive dense cores in the DR21 filament. The dust polarization shows complex magnetic field structures in the massive dense cores with sizes of 0.1 pc, in contrast to the ordered magnetic fields of the parsec-scale filament. The major axes of the massive dense cores appear to be aligned either parallel or perpendicular to the magnetic fields of the filament, indicating that the parsec-scale magnetic fields play an important role in the formation of the massive dense cores. However, the correlation between the major axes of the cores andmore » the magnetic fields of the cores is less significant, suggesting that during the core formation, the magnetic fields below 0.1 pc scales become less important than the magnetic fields above 0.1 pc scales in supporting a core against gravity. Our analysis of the angular dispersion functions of the observed polarization segments yields a plane-of-sky magnetic field strength of 0.4–1.7 mG for the massive dense cores. We estimate the kinematic, magnetic, and gravitational virial parameters of the filament and the cores. The virial parameters show that the gravitational energy in the filament dominates magnetic and kinematic energies, while the kinematic energy dominates in the cores. Our work suggests that although magnetic fields may play an important role in a collapsing filament, the kinematics arising from gravitational collapse must become more important than magnetic fields during the evolution from filaments to massive dense cores.« less

The evolution of compositionally and functionally distinct actin filaments.

PubMed

Gunning, Peter W; Ghoshdastider, Umesh; Whitaker, Shane; Popp, David; Robinson, Robert C

2015-06-01

The actin filament is astonishingly well conserved across a diverse set of eukaryotic species. It has essentially remained unchanged in the billion years that separate yeast, Arabidopsis and man. In contrast, bacterial actin-like proteins have diverged to the extreme, and many of them are not readily identified from sequence-based homology searches. Here, we present phylogenetic analyses that point to an evolutionary drive to diversify actin filament composition across kingdoms. Bacteria use a one-filament-one-function system to create distinct filament systems within a single cell. In contrast, eukaryotic actin is a universal force provider in a wide range of processes. In plants, there has been an expansion of the number of closely related actin genes, whereas in fungi and metazoa diversification in tropomyosins has increased the compositional variety in actin filament systems. Both mechanisms dictate the subset of actin-binding proteins that interact with each filament type, leading to specialization in function. In this Hypothesis, we thus propose that different mechanisms were selected in bacteria, plants and metazoa, which achieved actin filament compositional variation leading to the expansion of their functional diversity. © 2015. Published by The Company of Biologists Ltd.

Actin Filament Polymerization Regulates Gliding Motility by Apicomplexan ParasitesV⃞

PubMed Central

Wetzel, D.M.; Håkansson, S.; Hu, K.; Roos, D.; Sibley, L.D.

2003-01-01

Host cell entry by Toxoplasma gondii depends critically on actin filaments in the parasite, yet paradoxically, its actin is almost exclusively monomeric. In contrast to the absence of stable filaments in conventional samples, rapid-freeze electron microscopy revealed that actin filaments were formed beneath the plasma membrane of gliding parasites. To investigate the role of actin filaments in motility, we treated parasites with the filament-stabilizing drug jasplakinolide (JAS) and monitored the distribution of actin in live and fixed cells using yellow fluorescent protein (YFP)-actin. JAS treatment caused YFP-actin to redistribute to the apical and posterior ends, where filaments formed a spiral pattern subtending the plasma membrane. Although previous studies have suggested that JAS induces rigor, videomicroscopy demonstrated that JAS treatment increased the rate of parasite gliding by approximately threefold, indicating that filaments are rate limiting for motility. However, JAS also frequently reversed the normal direction of motility, disrupting forward migration and cell entry. Consistent with this alteration, subcortical filaments in JAS-treated parasites occurred in tangled plaques as opposed to the straight, roughly parallel orientation observed in control cells. These studies reveal that precisely controlled polymerization of actin filaments imparts the correct timing, duration, and directionality of gliding motility in the Apicomplexa. PMID:12589042

Plethora of transitions during breakup of liquid filaments

DOE PAGES

Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Thete, Sumeet Suresh; ...

2015-03-30

Thinning and breakup of liquid filaments are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the filament radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the filament breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the filament thins, viscous forcesmore » in the former case and inertial forces in the latter become important, and theory shows that the filament approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of filament radius well below that predicted by theory or is not observed. In this paper, we perform new simulations and experiments, and show that a thinning filament unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. Finally, the new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities.« less

Plethora of transitions during breakup of liquid filaments

PubMed Central

Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Thete, Sumeet Suresh; Sambath, Krishnaraj; Hutchings, Ian M.; Hinch, John; Lister, John R.; Basaran, Osman A.

2015-01-01

Thinning and breakup of liquid filaments are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the filament radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the governing equations become singular and the filament breaks. In slightly viscous liquids, thinning initially occurs in an inertial regime where inertial and capillary forces balance. By contrast, in highly viscous liquids, initial thinning occurs in a viscous regime where viscous and capillary forces balance. As the filament thins, viscous forces in the former case and inertial forces in the latter become important, and theory shows that the filament approaches breakup in the final inertial–viscous regime where all three forces balance. However, previous simulations and experiments reveal that transition from an initial to the final regime either occurs at a value of filament radius well below that predicted by theory or is not observed. Here, we perform new simulations and experiments, and show that a thinning filament unexpectedly passes through a number of intermediate transient regimes, thereby delaying onset of the inertial–viscous regime. The new findings have practical implications regarding formation of undesirable satellite droplets and also raise the question as to whether similar dynamical transitions arise in other free-surface flows such as coalescence that also exhibit singularities. PMID:25825761

Exploring the Dust Content of Galactic Winds with MIPS

NASA Astrophysics Data System (ADS)

Martin, Crystal; Engelbracht, Charles; Gordon, Karl

2005-06-01

This program explores the dust content of galactic winds. Nearly half of all stars in the universe probably form in a starburst event, where high concentrations of supernova explosions drive galactic-scale gaseous outflows. In nearby starburst galaxies, winds have been mapped at radio, optical, and X-ray frequencies revealing bipolar lobes of hot gas laced with cooler filaments bubbling out of the host galaxy. Most of the outflowing material is entrained interstellar gas, so it will remain quite dusty unless the grains are destroyed. Dusty winds have significant implications for the circulation of heavy elements in galaxies, the dust content of the intergalactic medium, and the acceleration of gaseous outflows. GALEX images of scattered ultraviolet light from galactic winds now provide compelling evidence for the survival of some grains. MIPS photometry of starburst winds at 24, 70, and 160 microns can, in principle, measure the dust temperature providing accurate estimates of the amount of dust (e.g. Engelbracht et al. 2004). To date, however, most MIPS observations of starburst galaxies are far too shallow to detect thermal emission from halo dust. The requested observations would provide the most sensitive observations currently possible for a sample of starburst galaxies, selected to span the full range of starburst luminosity and spatial geometry in the local universe.

Fabrication and assembly of the ERDA/NASA 100 kilowatt experimental wind turbine

NASA Technical Reports Server (NTRS)

Puthoff, R. L.

1976-01-01

As part of the Energy Research and Development Administration (ERDA) wind-energy program, NASA Lewis Research Center has designed and built an experimental 100-kW wind turbine. The two-bladed turbines drives a synchronous alternator that generates its maximum output of 100 kW of electrical power in a 29-km/hr (18-mph) wind. The design and assembly of the wind turbine were performed at Lewis from components that were procured from industry. The machine was installed atop the tower on September 3, 1975.

CAT-PUMA: CME Arrival Time Prediction Using Machine learning Algorithms

NASA Astrophysics Data System (ADS)

Liu, Jiajia; Ye, Yudong; Shen, Chenglong; Wang, Yuming; Erdélyi, Robert

2018-04-01

CAT-PUMA (CME Arrival Time Prediction Using Machine learning Algorithms) quickly and accurately predicts the arrival of Coronal Mass Ejections (CMEs) of CME arrival time. The software was trained via detailed analysis of CME features and solar wind parameters using 182 previously observed geo-effective partial-/full-halo CMEs and uses algorithms of the Support Vector Machine (SVM) to make its predictions, which can be made within minutes of providing the necessary input parameters of a CME.

Numerical model describing optimization of fibres winding process on open and closed frame

NASA Astrophysics Data System (ADS)

Petrů, M.; Mlýnek, J.; Martinec, T.

2016-08-01

This article discusses a numerical model describing optimization of fibres winding process on open and closed frame. The quality production of said type of composite frame depends primarily on the correct winding of fibers on a polyurethane core. It is especially needed to ensure the correct angles of the fibers winding on the polyurethane core and the homogeneity of individual winding layers. The article describes mathematical model for use an industrial robot in filament winding and how to calculate the trajectory of the robot. When winding fibers on the polyurethane core which is fastened to the robot-end-effector so that during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. We use the described numerical model and matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The calculation of the trajectory was programmed in the Delphi development environment. Relations of the numerical model are important for use a real solving of the passage of a polyurethane core through fibre-processing head.

Rotor Vortex Filaments: Living on the Slipstream's Edge

NASA Technical Reports Server (NTRS)

Young, Larry A.

1997-01-01

The purpose of this paper is to gain a better understanding of rotor wake evolution in hover and axial flow by deriving an analytical solution for the time dependent behavior of vortex filament circulation and core size. This solution is applicable only for vortex filaments in the rotor far-wake. A primarily inviscid vortex/shear layer interaction (where the slipstream boundary is modeled as a shear layer) has been identified in this analytical treatment. This vortex/shear layer interaction results in decreasing, vortex filament circulation and core size with time. The inviscid vortex/shear layer interaction is shown, in a first-order treatment, to be of greater magnitude than viscous diffusion effects. The rate of contraction, and ultimate collapse, of the vortex filament core is found to be directly proportional to the rotor inflow velocity. This new insight into vortex filament decay promises to help reconcile several disparate observations made in the literature and will, hopefully, promote new advances in theoretical modeling of rotor wakes.

National Wind Technology Center Dynamic 5-Megawatt Dynamometer

ScienceCinema

Felker, Fort

2018-06-06

The National Wind Technology Center (NWTC) offers wind industry engineers a unique opportunity to conduct a wide range of tests. Its custom-designed dynamometers can test wind turbine systems from 1 kilowatt (kW) to 5 megawatts (MW). The NWTC's new dynamometer facility simulates operating field conditions to assess the reliability and performance of wind turbine prototypes and commercial machines, thereby reducing deployment time, failures, and maintenance or replacement costs. Funded by the U.S. Department of Energy with American Recovery and Reinvestment Act (ARRA) funds, the 5-MW dynamometer will provide the ability to test wind turbine drivetrains and connect those drivetrains directly to the electricity grid or through a controllable grid interface (CGI). The CGI tests the low-voltage ride-through capability of a drivetrain as well as its response to faults and other abnormal grid conditions.

Proteomics of filamentous fungi.

PubMed

Kim, Yonghyun; Nandakumar, M P; Marten, Mark R

2007-09-01

Proteomic analysis, defined here as the global assessment of cellular proteins expressed in a particular biological state, is a powerful tool that can provide a systematic understanding of events at the molecular level. Proteomic studies of filamentous fungi have only recently begun to appear in the literature, despite the prevalence of these organisms in the biotechnology industry, and their importance as both human and plant pathogens. Here, we review recent publications that have used a proteomic approach to develop a better understanding of filamentous fungi, highlighting sample preparation methods and whole-cell cytoplasmic proteomics, as well as subproteomics of cell envelope, mitochondrial and secreted proteins.

Detection and characterization of multi-filament evolution during resistive switching

DOE PAGES

Mickel, Patrick R.; Lohn, Andrew J.; Marinella, Matthew J.

2014-08-05

We present resistive switching data in TaO x memristors displaying signatures of multi-filament switching modes, and develop a geometrically defined equivalent circuit to separate the individual resistances and powers dissipated in each filament. Using these resolved values, we compare the individual switching curves of each filament and demonstrate that the switching data of each filament collapse onto a single switching curve determined by the analytical steady-state resistive switching solution for filamentary switching. Analyzing our results in terms of this solution, we determine the switching temperature, heat flow, conductivity, and time evolving areas of each filament during resistive switching. Finally, wemore » discuss operational modes which may limit the formation of additional conducting filaments, potentially leading to increased device endurance.« less

Improved double-multiple streamtube model for the Darrieus-type vertical axis wind turbine

NASA Astrophysics Data System (ADS)

Berg, D. E.

Double streamtube codes model the curved blade (Darrieus-type) vertical axis wind turbine (VAWT) as a double actuator fish arrangement (one half) and use conservation of momentum principles to determine the forces acting on the turbine blades and the turbine performance. Sandia National Laboratories developed a double multiple streamtube model for the VAWT which incorporates the effects of the incident wind boundary layer, nonuniform velocity between the upwind and downwind sections of the rotor, dynamic stall effects and local blade Reynolds number variations. The theory underlying this VAWT model is described, as well as the code capabilities. Code results are compared with experimental data from two VAWT's and with the results from another double multiple streamtube and a vortex filament code. The effects of neglecting dynamic stall and horizontal wind velocity distribution are also illustrated.

Great geomagnetic storm of 9 November 1991: Association with a disappearing solar filament

NASA Astrophysics Data System (ADS)

Cliver, E. W.; Balasubramaniam, K. S.; Nitta, N. V.; Li, X.

2009-02-01

We attribute the great geomagnetic storm on 8-10 November 1991 to a large-scale eruption that encompassed the disappearance of a ~25° solar filament in the southern solar hemisphere. The resultant soft X-ray arcade spanned ~90° of solar longitude. The rapid growth of an active region lying at one end of the X-ray arcade appears to have triggered the eruption. This is the largest geomagnetic storm yet associated with the eruption of a quiescent filament. The minimum hourly Dst value of -354 nT on 9 November 1991 compares with a minimum Dst value of -161 nT for the largest 27-day recurrent (coronal hole) storm observed from 1972 to 2005 and the minimum -559 nT value observed during the flare-associated storm of 14 March 1989, the greatest magnetic storm recorded during the space age. Overall, the November 1991 storm ranks 15th on a list of Dst storms from 1905 to 2004, surpassing in intensity such well-known storms as 14 July 1982 (-310 nT) and 15 July 2000 (-317 nT). We used the Cliver et al. and Gopalswamy et al. empirical models of coronal mass ejection propagation in the solar wind to provide consistency checks on the eruption/storm association.

High Performance Computing for Modeling Wind Farms and Their Impact

NASA Astrophysics Data System (ADS)

Mavriplis, D.; Naughton, J. W.; Stoellinger, M. K.

2016-12-01

As energy generated by wind penetrates further into our electrical system, modeling of power production, power distribution, and the economic impact of wind-generated electricity is growing in importance. The models used for this work can range in fidelity from simple codes that run on a single computer to those that require high performance computing capabilities. Over the past several years, high fidelity models have been developed and deployed on the NCAR-Wyoming Supercomputing Center's Yellowstone machine. One of the primary modeling efforts focuses on developing the capability to compute the behavior of a wind farm in complex terrain under realistic atmospheric conditions. Fully modeling this system requires the simulation of continental flows to modeling the flow over a wind turbine blade, including down to the blade boundary level, fully 10 orders of magnitude in scale. To accomplish this, the simulations are broken up by scale, with information from the larger scales being passed to the lower scale models. In the code being developed, four scale levels are included: the continental weather scale, the local atmospheric flow in complex terrain, the wind plant scale, and the turbine scale. The current state of the models in the latter three scales will be discussed. These simulations are based on a high-order accurate dynamic overset and adaptive mesh approach, which runs at large scale on the NWSC Yellowstone machine. A second effort on modeling the economic impact of new wind development as well as improvement in wind plant performance and enhancements to the transmission infrastructure will also be discussed.

Filamentous bacteria existence in aerobic granular reactors.

PubMed

Figueroa, M; Val del Río, A; Campos, J L; Méndez, R; Mosquera-Corral, A

2015-05-01

Filamentous bacteria are associated to biomass settling problems in wastewater treatment plants. In systems based on aerobic granular biomass they have been proposed to contribute to the initial biomass aggregation process. However, their development on mature aerobic granular systems has not been sufficiently studied. In the present research work, filamentous bacteria were studied for the first time after long-term operation (up to 300 days) of aerobic granular systems. Chloroflexi and Sphaerotilus natans have been observed in a reactor fed with synthetic wastewater. These filamentous bacteria could only come from the inoculated sludge. Thiothrix and Chloroflexi bacteria were observed in aerobic granular biomass treating wastewater from a fish canning industry. Meganema perideroedes was detected in a reactor treating wastewater from a plant processing marine products. As a conclusion, the source of filamentous bacteria in these mature aerobic granular systems fed with industrial effluents was the incoming wastewater.

Oriented thick and thin filaments in amoeba proteus

PubMed Central

Rinaldi, RA; Hrebenda, B

1975-01-01

Actin and myosin filaments as a foundation of contractile systems are well established from ameba to man (3). Wolpert et al. (19) isolated by differential centrifugation from Amoeba proteus a motile fraction composed of filaments which moved upon the addition of ATP. Actin filaments are found in amebas (1, 12, 13) which react with vertebrate heavy meromyosin (HMM), forming arrowhead complexes as vertebrate actin (3, 9), and are prominent within the ectoplasmic tube where some of them are attached to the plasmalemma (1, 12). Thick and thin filaments possessing the morphological characteristics of myosin and actin have been obtained from isolated ameba cytoplasm (18, 19). In addition, there are filaments exhibiting ATPase activity in amebas which react with actin (12, 16, 17). However, giant ameba (Chaos-proteus) shapes are difficult to preserve, and the excellent contributions referred to above are limited by visible distortions occurring in the amebas (rounding up, pseudopods disappearing, and cellular organelles swelling) upon fixation. Achievement of normal ameboid shape in recent glycerination work (15) led us to attempt other electron microscope fixation techniques, resulting in a surprising preservation of A. proteus with a unique orientation of thick and thin filaments in the ectoplasmic region. PMID:1141376

Model-based analysis of keratin intermediate filament assembly

NASA Astrophysics Data System (ADS)

Martin, Ines; Leitner, Anke; Walther, Paul; Herrmann, Harald; Marti, Othmar

2015-09-01

The cytoskeleton of epithelial cells consists of three types of filament systems: microtubules, actin filaments and intermediate filaments (IFs). Here, we took a closer look at type I and type II IF proteins, i.e. keratins. They are hallmark constituents of epithelial cells and are responsible for the generation of stiffness, the cellular response to mechanical stimuli and the integrity of entire cell layers. Thereby, keratin networks constitute an important instrument for cells to adapt to their environment. In particular, we applied models to characterize the assembly of keratin K8 and K18 into elongated filaments as a means for network formation. For this purpose, we measured the length of in vitro assembled keratin K8/K18 filaments by transmission electron microscopy at different time points. We evaluated the experimental data of the longitudinal annealing reaction using two models from polymer chemistry: the Schulz-Zimm model and the condensation polymerization model. In both scenarios one has to make assumptions about the reaction process. We compare how well the models fit the measured data and thus determine which assumptions fit best. Based on mathematical modelling of experimental filament assembly data we define basic mechanistic properties of the elongation reaction process.

Lighting the universe with filaments.

PubMed

Gao, Liang; Theuns, Tom

2007-09-14

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

Adaptive virus detection using filament-coupled antibodies.

PubMed

Stone, Gregory P; Lin, Kelvin S; Haselton, Frederick R

2006-01-01

We recently reported the development of a filament-antibody recognition assay (FARA), in which the presence of virions in solution initiates the formation of enzyme-linked immunosorbent assay (ELISA)-like antibody complexes. The unique features of this assay are that processing is achieved by motion of a filament and that, in the presence of a virus, antibody-virus complexes are coupled to the filament at known locations. In this work, we combine the unique features of this assay with a 638-nm laser-based optical detector to enable adaptive control of virus detection. Integration of on-line fluorescence detection yields approximately a five-fold increase in signal-to-noise ratio (SNR) compared to the fluorescence detection method reported previously. A one-minute incubation with an M13K07 test virus is required to detect 10(10) virionsml, and 40 min was required to detect 10(8) virionsml. In tests of the components of an adaptive strategy, a 30-min virus (3.3 x 10(10) virionsml) incubation time, followed by repositioning the filament-captured virus either within the detecting antibody chamber, (20 microg ml) or within the virus chamber, found an increase in signal roughly proportional to the cumulative residence times in these chambers. Furthermore, cumulative fluorescence signals observed for a filament-captured virus after repeated positioning of the filament within the virus chamber are similar to those observed for a single long incubation time. The unique features of the FARA-like design combined with online optical detection to direct subsequent bioprocessing steps provides new flexibility for developing adaptive molecular recognition assays.

Filamentous actin organization in the unfertilized sea urchin egg cortex.

PubMed

Henson, J H; Begg, D A

1988-06-01

We have investigated the organization of filamentous actin in the cortex of unfertilized eggs of the sea urchins Strongylocentrotus purpuratus and Lytechinus variegatus. Rhodamine phalloidin and anti-actin immunofluorescent staining of isolated cortices reveal a punctate pattern of fluorescent sources. Comparison of this pattern with SEM images of microvillar morphology and distribution indicates that filamentous actin in the cortex is predominantly localized in the microvilli. Thin-section TEM and quick-freeze deep-etch ultrastructure of isolated cortices demonstrates that this microvillar-associated actin is in a novel organizational state composed of very short filaments arranged in a tight network and that these filament networks form mounds that extend beyond the plane of the plasma membrane. Actin filaments within the networks do not exhibit free ends and make end-on attachments with the membrane only within the region of the evaginating microvilli. Myosin S-1 dissociable crosslinks, 2-3 nm in diameter, are observed between network filaments and between network filaments and the membrane. A second population of long, individual actin filaments is observed in close lateral association with the plasma membrane and frequently complexes with the microvillar actin networks. The filamentous actin of the unfertilized egg cortex may participate in establishing the mechanical properties of the egg surface and may function in nucleating the assembly of cortical actin following fertilization.

Material Supply and Magnetic Configuration of an Active Region Filament

NASA Astrophysics Data System (ADS)

Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda

2016-11-01

It is important to study the fine structures of solar filaments with high-resolution observations, since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly formed filament located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool material is seen to be injected into the filament spine with a speed of 5-10 km s-1. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the filament with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the filament, with the plane-of-the-sky speed being 7-9 km s-1 in the Hα red-wing filtergrams and 9-25 km s-1 in the blue-wing filtergrams. The observations are indicative that this active region filament is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of filament threads as in many other filaments.

Assessing the representativeness of wind data for wind turbine site evaluation

NASA Technical Reports Server (NTRS)

Renne, D. S.; Corotis, R. B.

1982-01-01

Once potential wind turbine sites (either for single installations or clusters) are identified through siting procedures, actual evaluation of the sites must commence. This evaluation is needed to obtain estimates of wind turbine performance and to identify hazards to the machine from the turbulence component of the atmosphere. These estimates allow for more detailed project planning and for preliminary financing arrangements to be secured. The site evaluation process can occur in two stages: (1) utilizing existing nearby data, and (2) establishing and monitoring an onsite measurement program. Since step (2) requires a period of at least 1 yr or more from the time a potential site has been identified, step (1) is often an essential stage in the preliminary evaluation process. Both the methods that have been developed and the unknowns that still exist in assessing the representativeness of available data to a nearby wind turbine site are discussed. How the assessment of the representativeness of available data can be used to develop a more effective onsite meteorological measurement program is also discussed.

The Cape Ghir filament system in August 2009 (NW Africa)

NASA Astrophysics Data System (ADS)

Sangrà, Pablo; Troupin, Charles; Barreiro-González, Beatriz; Desmond Barton, Eric; Orbi, Abdellatif; Arístegui, Javier

2015-06-01

In the framework of the Canaries-Iberian marine ecosystem Exchanges (CAIBEX) experiment, an interdisciplinary high-resolution survey was conducted in the NW African region of Cape Ghir (30°38'N) during August 2009. The anatomy of a major filament is investigated on scales down to the submesoscale using in situ and remotely sensed data. The filament may be viewed as a system composed of three intimately connected structures: a small, shallow, and cold filament embedded within a larger, deeper, and cool filament and an intrathermocline anticyclonic eddy (ITE). The cold filament, which stretches 110 km offshore, is a shallow feature 60 m deep and 25 km wide, identified by minimal surface temperatures and rich in chlorophyll a. This structure comprises two asymmetrical submesoscale (˜18 km) fronts with jets flowing in opposite directions. The cold filament is embedded near the equatorward boundary of a much broader region of approximately 120 km width and 150 m depth that forms the cool filament and stretches at least 200 km offshore. This cool region, partly resulting from the influence of cold filament, is limited by two asymmetrical mesoscale (˜50 km) frontal boundaries. At the ITE, located north of the cold filament, we observe evidence of downwelling as indicated by a relatively high concentration of particles extending from the surface to more than 200 m depth. We hypothesize that this ITE may act as a sink of carbon and thus the filament system may serve dual roles of offshore carbon export and carbon sink.

Design and Analysis of Linear Fault-Tolerant Permanent-Magnet Vernier Machines

PubMed Central

Xu, Liang; Liu, Guohai; Du, Yi; Liu, Hu

2014-01-01

This paper proposes a new linear fault-tolerant permanent-magnet (PM) vernier (LFTPMV) machine, which can offer high thrust by using the magnetic gear effect. Both PMs and windings of the proposed machine are on short mover, while the long stator is only manufactured from iron. Hence, the proposed machine is very suitable for long stroke system applications. The key of this machine is that the magnetizer splits the two movers with modular and complementary structures. Hence, the proposed machine offers improved symmetrical and sinusoidal back electromotive force waveform and reduced detent force. Furthermore, owing to the complementary structure, the proposed machine possesses favorable fault-tolerant capability, namely, independent phases. In particular, differing from the existing fault-tolerant machines, the proposed machine offers fault tolerance without sacrificing thrust density. This is because neither fault-tolerant teeth nor the flux-barriers are adopted. The electromagnetic characteristics of the proposed machine are analyzed using the time-stepping finite-element method, which verifies the effectiveness of the theoretical analysis. PMID:24982959

Utility experience with two demonstration wind turbine generators

NASA Astrophysics Data System (ADS)

Wehrey, M. C.

Edison has committed 360 MW of nameplate generating capacity to wind energy by year 1990 in its long-range generation plan. To reach this goal the Company's wind energy program focuses on three areas: the continuous evaluation of the wind resource, the hands-on demonstration of wind turbine generators (WTG) and an association with wind park developers. Two demonstration WTGs have been installed and operated at Edison's Wind Energy Center near Palm Springs, California: a 3 MW horizontal axis Bendix/Schachle WTG and a 500 kW vertical axis Alcoa WTG. They are part of a one to two year test program during which the performance of the WTGs will be evaluated, their system operation and environmental impact will be assessed and the design criteria of future WTGs will be identified. Edison's experience with these two WTGs is summarized and the problems encountered with the operation of the two machines are discussed.

Utility experience with two demonstration wind turbine generators

NASA Technical Reports Server (NTRS)

Wehrey, M. C.

1982-01-01

Edison has committed 360 MW of nameplate generating capacity to wind energy by year 1990 in its long-range generation plan. To reach this goal the Company's wind energy program focuses on three areas: the continuous evaluation of the wind resource, the hands-on demonstration of wind turbine generators (WTG) and an association with wind park developers. Two demonstration WTGs have been installed and operated at Edison's Wind Energy Center near Palm Springs, California: a 3 MW horizontal axis Bendix/Schachle WTG and a 500 kW vertical axis Alcoa WTG. They are part of a one to two year test program during which the performance of the WTGs will be evaluated, their system operation and environmental impact will be assessed and the design criteria of future WTGs will be identified. Edison's experience with these two WTGs is summarized and the problems encountered with the operation of the two machines are discussed.

Multi-parameter monitoring of electrical machines using integrated fibre Bragg gratings

NASA Astrophysics Data System (ADS)

Fabian, Matthias; Hind, David; Gerada, Chris; Sun, Tong; Grattan, Kenneth T. V.

2017-04-01

In this paper a sensor system for multi-parameter electrical machine condition monitoring is reported. The proposed FBG-based system allows for the simultaneous monitoring of machine vibration, rotor speed and position, torque, spinning direction, temperature distribution along the stator windings and on the rotor surface as well as the stator wave frequency. This all-optical sensing solution reduces the component count of conventional sensor systems, i.e., all 48 sensing elements are contained within the machine operated by a single sensing interrogation unit. In this work, the sensing system has been successfully integrated into and tested on a permanent magnet motor prototype.

Wind energy converter GROWIAN 2

NASA Astrophysics Data System (ADS)

Braun, D.; Kloeppel, V.; Marsch, G.; Meggle, R.; Mehlhose, R.; Schoebe, B.; Wennekers, R.

1984-04-01

Multi MW wind energy conversion systems in the rotor class of 135 m diam are described. A variable-speed horizontal-axis downwind machine with a one-bladed teetering rotor and a guyed soft steel tower was investigated and a 1 to 3 scaled demonstrator with a rotor diameter of 48 m was built. The demonstrator will undergo a 2 year verification test program.

The effective resistance between twisted superconducting filaments in tapes

NASA Astrophysics Data System (ADS)

Takács, S.; Iwakuma, M.; Funaki, K.

2001-05-01

We consider two mechanisms, which influence the effective resistance between crossing strands on flat cables or filaments in twisted tapes. The one-layer classical Rutherford-type cable and the tapes with twisted BSCCO filaments in silver matrix are taken as analogous cases. The amount of the matrix between strands or filaments increases the effective conductance compared with the direct current paths (determined by the touching area of the filaments). The increase factor is about two and can easily be suppressed by other effects, like the contact resistance between the superconductor and the matrix. The second mechanism is due to the existence of induced voltage between any points of crossing filaments. This leads to an additional effective conductance, proportional to the square of the total number of filaments. Both effects are not very important for isotropic superconductors, but due to the strong anisotropy of critical parameters they can dominate for high temperature superconductors. The first one may partially compensate the influence of the usually weaker critical current density perpendicular to the tape. The contribution due to the second effect can explain the higher resistivity of the matrix in BSCCO tapes compared with pure silver. It seems that to obtain low AC coupling losses in BSCCO tapes, structures with small filament number are required.

Waving of filaments induced by molecular motors

NASA Astrophysics Data System (ADS)

de Canio, Gabriele; Lauga, Eric; Goldstein, Raymond E.

2017-11-01

In many cellular phenomena, for example cytoplasmic streaming, molecular motors translocate along microtubules carrying cargoes which entrain fluid. The piconewton forces that motors produce can be sufficient to bend or buckle the filaments. When large numbers of such forced filaments interact through the surrounding fluid, as in particular stages of oocyte development in Drosophila melanogaster, complex dynamics are observed, but the mechanism underlying them has remained unclear. By using a combination of theory and numerical simulations, we study a simplified microtubules-molecular motor system in a viscous fluid and show that it can capture the wave-like filament motion dynamics observed in experiments.

Nonlinear Binormal Flow of Vortex Filaments

NASA Astrophysics Data System (ADS)

Strong, Scott; Carr, Lincoln

2015-11-01

With the current advances in vortex imaging of Bose-Einstein condensates occurring at the Universities of Arizona, São Paulo and Cambridge, interest in vortex filament dynamics is experiencing a resurgence. Recent simulations, Salman (2013), depict dissipative mechanisms resulting from vortex ring emissions and Kelvin wave generation associated with vortex self-intersections. As the local induction approximation fails to capture reconnection events, it lacks a similar dissipative mechanism. On the other hand, Strong&Carr (2012) showed that the exact representation of the velocity field induced by a curved segment of vortex contains higher-order corrections expressed in powers of curvature. This nonlinear binormal flow can be transformed, Hasimoto (1972), into a fully nonlinear equation of Schrödinger type. Continued transformation, Madelung (1926), reveals that the filament's square curvature obeys a quasilinear scalar conservation law with source term. This implies a broader range of filament dynamics than is possible with the integrable linear binormal flow. In this talk we show the affect higher-order corrections have on filament dynamics and discuss physical scales for which they may be witnessed in future experiments. Partially supported by NSF.

Mapping the filaments in NGC 1275

NASA Astrophysics Data System (ADS)

Cobos, Aracely Susan; Rich, Jeffrey; Great Observatories All-sky LIRG Survey (GOALS)

2018-01-01

The giant elliptical brightest cluster galaxies (BCGs) at the centers of many massive clusters are often surrounded by drawn-out forms of gaseous material. It is believed that this gaseous material is gas condensing from the intracluster medium (ICM) in a “cooling flow,” and it can directly impact the growth of the BCG. The galaxy NGC 1275 is one of the closest giant elliptical BCGs and lies at the center of the Perseus cluster. NGC 1275 has large filaments that are thought to be associated with a cooling flow, but they may also be affected by its AGN. To investigate the relationship between the AGN and the cooling flow we have mapped the filaments around NGC 1275 with the Cosmic Web Imager, an image-slicing integral field spectrograph at Palomar Observatories. We employ standard emission-line ratio diagnostics to determine the source of ionizing radiation. We use our analysis to investigate whether the formation of the extended filaments is a result of gas from the ICM collapsing onto the galaxy as it cools or if it is possible that the filaments are a result of the cluster’s interaction with the outflow driven by the AGN.

Intermediate filament mechanics in vitro and in the cell: from coiled coils to filaments, fibers and networks.

PubMed

Köster, Sarah; Weitz, David A; Goldman, Robert D; Aebi, Ueli; Herrmann, Harald

2015-02-01

Intermediate filament proteins form filaments, fibers and networks both in the cytoplasm and the nucleus of metazoan cells. Their general structural building plan accommodates highly varying amino acid sequences to yield extended dimeric α-helical coiled coils of highly conserved design. These 'rod' particles are the basic building blocks of intrinsically flexible, filamentous structures that are able to resist high mechanical stresses, that is, bending and stretching to a considerable degree, both in vitro and in the cell. Biophysical and computer modeling studies are beginning to unfold detailed structural and mechanical insights into these major supramolecular assemblies of cell architecture, not only in the 'test tube' but also in the cellular and tissue context. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Machine LearningFramework to Forecast Wave Conditions

NASA Astrophysics Data System (ADS)

Zhang, Y.; James, S. C.; O'Donncha, F.

2017-12-01

Recently, significant effort has been undertaken to quantify and extract wave energy because it is renewable, environmental friendly, abundant, and often close to population centers. However, a major challenge is the ability to accurately and quickly predict energy production, especially across a 48-hour cycle. Accurate forecasting of wave conditions is a challenging undertaking that typically involves solving the spectral action-balance equation on a discretized grid with high spatial resolution. The nature of the computations typically demands high-performance computing infrastructure. Using a case-study site at Monterey Bay, California, a machine learning framework was trained to replicate numerically simulated wave conditions at a fraction of the typical computational cost. Specifically, the physics-based Simulating WAves Nearshore (SWAN) model, driven by measured wave conditions, nowcast ocean currents, and wind data, was used to generate training data for machine learning algorithms. The model was run between April 1st, 2013 and May 31st, 2017 generating forecasts at three-hour intervals yielding 11,078 distinct model outputs. SWAN-generated fields of 3,104 wave heights and a characteristic period could be replicated through simple matrix multiplications using the mapping matrices from machine learning algorithms. In fact, wave-height RMSEs from the machine learning algorithms (9 cm) were less than those for the SWAN model-verification exercise where those simulations were compared to buoy wave data within the model domain (>40 cm). The validated machine learning approach, which acts as an accurate surrogate for the SWAN model, can now be used to perform real-time forecasts of wave conditions for the next 48 hours using available forecasted boundary wave conditions, ocean currents, and winds. This solution has obvious applications to wave-energy generation as accurate wave conditions can be forecasted with over a three-order-of-magnitude reduction in

Torque ripple reduction in electric machines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, Patel Bhageerath; Huh, Kum-Kang; El-Refaie, Ayman Mohamed Fawzi

An electric machine, such as an Internal Permanent magnet or Synchronous Reluctance machine, having X phases, that includes a stator assembly, having M slots, with a stator core and stator teeth, that is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface that defines a cavity; and a rotor assembly, having N poles, disposed within the cavity which is configured to rotate about the longitudinal axis, wherein the rotor assembly includes a shaft, a rotor core located circumferentially around the shaft. The machinemore » is configured such that a value k=M/(X*N) wherein k is a non-integer greater than about 1.3. The electric machine may alternatively, or additionally, include a non-uniformed gap between the exterior surface of the rotor spokes and the interior stator surface of the stator.« less

Desmin filaments studied by quasi-elastic light scattering.

PubMed Central

Hohenadl, M; Storz, T; Kirpal, H; Kroy, K; Merkel, R

1999-01-01

We studied polymers of desmin, a muscle-specific type III intermediate filament protein, using quasi-elastic light scattering. Desmin was purified from chicken gizzard. Polymerization was induced either by 2 mM MgCl(2) or 150 mM NaCl. The polymer solutions were in the semidilute regime. We concluded that the persistence length of the filaments is between 0.1 and 1 microm. In all cases, we found a hydrodynamic diameter of desmin filaments of 16-18 nm. The filament dynamics exhibits a characteristic frequency in the sense that correlation functions measured on one sample but at different scattering vectors collapse onto a single master curve when time is normalized by the experimentally determined initial decay rate. PMID:10512839

Stereoscopic Analysis of 19 May and 31 Aug 2007 Filament Eruptions

NASA Technical Reports Server (NTRS)

Liewer, Paulett; DeJong, E. M.; Hall, J. R.

2008-01-01

The presentation outline includes results from stereoscopic analysis of SECCHI/EUVI data for 19 May 2007 filament eruption, including the determined 3D trajectory of erupting filament, strong evidence for reconnection below erupting filament as consistent with standard model, and comparison of EUVI and H-alpha images during eruption; and results from stereoscopic analytic of 21 August 2007 filament eruption. Slide topics include standard model of filament eruption; 2007 May 19 STEREO A/SECCHI/EUVI 195 and 304 A: CME signatures and filament eruption, 3D reconstruction of erupting prominence; filament's relation to coronal magnetic fields; 3d reconstructions of filament eruption; height-time plot of eruption from 3D reconstructions; detailed pre-eruptions comparison of H-alpha and EUVI 304 at 12:42 UT; comparisons during the eruption; STEREO prominence and CME August 31, 2007; reconstructions of prominence and leading edges of both dark cavity and CME; and 3D reconstructions of prominence and leading edges.

Design and operating experience on the U.S. Department of Energy Experimental Mod-O 100 kW Wind Turbine

NASA Technical Reports Server (NTRS)

Glasgow, J. C.; Birchenough, A. G.

1978-01-01

The Mod-O 100 kW Experimental Wind Turbine was designed and fabricated by NASA, as part of the Federal Wind Energy Program, to assess technology requirements and engineering problems of large wind turbines. The machine became operational in October 1975 and has demonstrated successful operation in all of its design modes. During the course of its operations the machine has generated a wealth of experimental data and has served as a prototype developmental test bed for the Mod-OA operational wind turbines which are currently used on utility networks. This paper describes the mechanical and control systems as they evolved in operational tests and describes some of the experience with various systems in the downwind rotor configuration.

Impact of matric potential and pore size distribution on growth dynamics of filamentous and non-filamentous soil bacteria.

PubMed

Wolf, Alexandra B; Vos, Michiel; de Boer, Wietse; Kowalchuk, George A

2013-01-01

The filamentous growth form is an important strategy for soil microbes to bridge air-filled pores in unsaturated soils. In particular, fungi perform better than bacteria in soils during drought, a property that has been ascribed to the hyphal growth form of fungi. However, it is unknown if, and to what extent, filamentous bacteria may also display similar advantages over non-filamentous bacteria in soils with low hydraulic connectivity. In addition to allowing for microbial interactions and competition across connected micro-sites, water films also facilitate the motility of non-filamentous bacteria. To examine these issues, we constructed and characterized a series of quartz sand microcosms differing in matric potential and pore size distribution and, consequently, in connection of micro-habitats via water films. Our sand microcosms were used to examine the individual and competitive responses of a filamentous bacterium (Streptomyces atratus) and a motile rod-shaped bacterium (Bacillus weihenstephanensis) to differences in pore sizes and matric potential. The Bacillus strain had an initial advantage in all sand microcosms, which could be attributed to its faster growth rate. At later stages of the incubation, Streptomyces became dominant in microcosms with low connectivity (coarse pores and dry conditions). These data, combined with information on bacterial motility (expansion potential) across a range of pore-size and moisture conditions, suggest that, like their much larger fungal counterparts, filamentous bacteria also use this growth form to facilitate growth and expansion under conditions of low hydraulic conductivity. The sand microcosm system developed and used in this study allowed for precise manipulation of hydraulic properties and pore size distribution, thereby providing a useful approach for future examinations of how these properties influence the composition, diversity and function of soil-borne microbial communities.

Constitutive Models for the Force-Extension Behavior of Biological Filaments

NASA Astrophysics Data System (ADS)

Palmer, J. S.; Castro, C. E.; Arslan, M.; Boyce, M. C.

Biopolymer filaments form the molecular backbone of biological structures throughout the body. The biomechanical response of single filaments yields insight into their individual behavior at the molecular level as well as their concerted networked behavior at the cellular and tissue scales. This paper focuses on modeling approaches for axial force vs. extension behavior of single biopolymer filaments within three stiffness regimes: flexible, semiflexible, and stiff. The end-to-end force-extension behaviors of flexible and semiflexible filaments arise as a result of a reduction in configurational space as the filament is straightened and are captured with entropic models including the freely jointed chain model and the worm-like chain model. As the filament is straightened and the end-to-end distance approaches the filament contour length, the contour length is directly axially extended and an internal energy contribution governs the force-extension behavior in this limiting extension regime. On the other hand, for stiff filaments in originally crimped or kinked configurations, the end-to-end force vs. extension behavior results from the unbending (straightening) of the crimped configuration as governed by an internal energy based elastica approximation which is also complemented by an axial stretching contribution once the end-to-end distance approaches the contour length of the filament. Simplified, analytical force-extension relationships are developed for the worm-like chain model for semiflexible filaments, and for the Euler elastica model for stiffer, wavy fibers. For the case of flexible molecules containing modular folded domains, the influence of force-induced unfolding on the force-extension behavior of single molecules and assemblies of multiple molecules is also presented.

Electron emission controller with pulsed heating of filament

NASA Astrophysics Data System (ADS)

Durakiewicz, Tomasz

1996-11-01

A novel circuit has been invented for the versatile and safe stabilization of the electron emission current (Ie) produced by a hot filament in mass spectrometers or in ionization gauges. The voltage signal, which is directly proportional to Ie, is provided to the inverting input of a comparator, whereas the noninverting input is connected to the reference voltage. In addition to the commonly used negative feedback loop, a positive feedback loop was introduced by siting a resistor between the noninverting input and the output of the comparator, which results in a pulsation of the filament voltage. The pulses are rectangular, so that the power dissipated by the transistor in the filament power supply circuit is radically reduced. To refine the switching action of the transistor, the output of the comparator is connected through a capacitor to the transistor gate. A concise discussion of the phase shift between Ie, the filament temperature Tf, and the filament voltage Vf, including time constants for different modes of power dissipation, is included.

Tropomyosin inhibits ADF/cofilin-dependent actin filament dynamics.

PubMed

Ono, Shoichiro; Ono, Kanako

2002-03-18

Tropomyosin binds to actin filaments and is implicated in stabilization of actin cytoskeleton. We examined biochemical and cell biological properties of Caenorhabditis elegans tropomyosin (CeTM) and obtained evidence that CeTM is antagonistic to ADF/cofilin-dependent actin filament dynamics. We purified CeTM, actin, and UNC-60B (a muscle-specific ADF/cofilin isoform), all of which are derived from C. elegans, and showed that CeTM and UNC-60B bound to F-actin in a mutually exclusive manner. CeTM inhibited UNC-60B-induced actin depolymerization and enhancement of actin polymerization. Within isolated native thin filaments, actin and CeTM were detected as major components, whereas UNC-60B was present at a trace amount. Purified UNC-60B was unable to interact with the native thin filaments unless CeTM and other associated proteins were removed by high-salt extraction. Purified CeTM was sufficient to restore the resistance of the salt-extracted filaments from UNC-60B. In muscle cells, CeTM and UNC-60B were localized in different patterns. Suppression of CeTM by RNA interference resulted in disorganized actin filaments and paralyzed worms in wild-type background. However, in an ADF/cofilin mutant background, suppression of CeTM did not worsen actin organization and worm motility. These results suggest that tropomyosin is a physiological inhibitor of ADF/cofilin-dependent actin dynamics.

Features of the impact of the solar wind diamagnetic structure on Earth's magnetosphere

NASA Astrophysics Data System (ADS)

Parhomov, Vladimir; Borodkova, Natalia; Eselevich, Viktor; Eselevich, Maxim; Dmitriev, Aleksey; Chilikin, Vitaliy

2017-12-01

At Earth's orbit on June 28, 1999, there was a diamagnetic structure (DS) representing a filament with a uniquely high speed (about 900 km/s). We show that the filament is a part of the specific sporadic solar wind (SW) stream, which is characterized as a small interplanetary transient. We report the results of studies on the interaction between such a fast filament (DS) and Earth's magnetosphere. Around noon hours at daytime cusp latitudes, we recorded a powerful aurora in the UV band (shock aurora), which rapidly spread to the west and east. Ground-based observations of geo-magnetic field variations, auroral absorption, and auroras on the midnight meridian have shown the development of a powerful substorm-like disturbance (SLD) (AE∼1000 nT), whose origin is associated with the impact of the SW diamagnetic structure on the magnetosphere. The geostationary satellite GOES-8, which was in the midnight sector of the outer quasi capture region during SLD, recorded variations of the Bz and Bx geomagnetic components corresponding to the dipolization process.

Traceability of On-Machine Tool Measurement: A Review.

PubMed

Mutilba, Unai; Gomez-Acedo, Eneko; Kortaberria, Gorka; Olarra, Aitor; Yagüe-Fabra, Jose A

2017-07-11

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand.

Traceability of On-Machine Tool Measurement: A Review

PubMed Central

Gomez-Acedo, Eneko; Kortaberria, Gorka; Olarra, Aitor

2017-01-01

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand. PMID:28696358

Investigation of the corneal filament in filamentary keratitis.

PubMed

Tanioka, Hidetoshi; Yokoi, Norihiko; Komuro, Aoi; Shimamoto, Takasumi; Kawasaki, Satoshi; Matsuda, Akira; Kinoshita, Shigeru

2009-08-01

To date, no studies have elucidated the composition of the corneal filament in detail. In this study, an immunohistochemical technique was used to clarify the exact composition of the corneal filament in filamentary keratitis. In addition, the mechanisms responsible for filament formation were identified. Filaments were obtained from 13 patients with filamentary keratitis with a background of penetrating keratoplasty, aqueous tear deficiency, and severe ocular surface disorders, who were receiving treatment at an outpatient facility. From those tissues, transverse and longitudinal frozen sections were prepared and subjected to an indirect fluorescent immunohistochemical analysis with primary antibodies, including cytokeratins (CK1, -4, -6, -10, -12, and -13), mucins (MUC1, -4, -5AC, and -16), keratinization-related proteins (transglutaminase [TGase]-1 and filaggrin), cell proliferation marker Ki67, and markers of infiltration cells (HLA-DR and neutrophil-elastase). TUNEL staining was used for the detection of apoptosis. Fluorescent images of the sections were inspected with a fluorescence microscope. The filaments were composed of CK12-positive cells and had a roll-formed central core. They were covered with MUC5AC- and -16-positive mucins including CK4- and -13-positive cells and neutrophil-elastase-positive cells. The filaments also included broken cells and DNA fiber-form postlesional nuclei that were positive for TUNEL staining. However, those areas stained weakly for CK6 and HLA-DR; faintly for CK1, CK10, MUC1, and MUC4; and not at all for Ki67, TGase-1, and filaggrin. The results of this research have the potential to open new pathways toward understanding the mechanism that generates the filament in filamentary keratitis, as well as new treatments in the future.

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.

The Role of Magnetic Fields in High-Mass Star-Forming Filaments

NASA Astrophysics Data System (ADS)

Stephens, Ian

2015-10-01

Filaments are ubiquitous in the star formation process. Planck has revealed that magnetic fields are perpendicular to the densest filaments, which are the birthplace of high-mass stars, suggesting that fields help funnel gas into the filaments. However, the resolved field morphologies and strengths in the dense filaments are unknown. We propose HAWC+ 53 and 214 um polarimetric observations toward two filaments, the Snake (G11.1) and G18.6, to unveil the field morphology. Such observations will probe the filament field morphology at the subarcminute scale over the largest spatial extent to date: 25 and 9 pc respectively. We expect to have over 400 independent beams worth of detections. From the field morphology, we will test the hub-filament theory and investigate how the magnetic field strength and morphology changes with evolution and size-scale.

The Role of Magnetic Fields in High-Mass Star-Forming Filaments

NASA Astrophysics Data System (ADS)

Stephens, Ian

Filaments are ubiquitous in the star formation process. Planck has revealed that magnetic fields are perpendicular to the densest filaments, which are the birthplace of high-mass stars, suggesting that fields help funnel gas into the filaments. However, the resolved field morphologies and strengths in the dense filaments are unknown. We propose HAWC+ 53 and 214 um polarimetric observations toward two filaments, the Snake (G11.1) and G18.6, to unveil the field morphology. Such observations will probe the filament field morphology at the subarcminute scale over the largest spatial extent to date: 25 and 9 pc respectively. We expect to have over 400 independent beams worth of detections. From the field morphology, we will test the hub-filament theory and investigate how the magnetic field strength and morphology changes with evolution and size-scale.

Convective Heat Transfer Coefficients of Automatic Transmission Fluid Jets with Implications for Electric Machine Thermal Management: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennion, Kevin; Moreno, Gilberto

2015-09-29

Thermal management for electric machines (motors/ generators) is important as the automotive industry continues to transition to more electrically dominant vehicle propulsion systems. Cooling of the electric machine(s) in some electric vehicle traction drive applications is accomplished by impinging automatic transmission fluid (ATF) jets onto the machine's copper windings. In this study, we provide the results of experiments characterizing the thermal performance of ATF jets on surfaces representative of windings, using Ford's Mercon LV ATF. Experiments were carried out at various ATF temperatures and jet velocities to quantify the influence of these parameters on heat transfer coefficients. Fluid temperatures weremore » varied from 50 degrees C to 90 degrees C to encompass potential operating temperatures within an automotive transaxle environment. The jet nozzle velocities were varied from 0.5 to 10 m/s. The experimental ATF heat transfer coefficient results provided in this report are a useful resource for understanding factors that influence the performance of ATF-based cooling systems for electric machines.« less

Health Risks Associated with Exposure to Filamentous Fungi

PubMed Central

Egbuta, Mary Augustina; Mwanza, Mulunda

2017-01-01

Filamentous fungi occur widely in the environment, contaminating soil, air, food and other substrates. Due to their wide distribution, they have medical and economic implications. Regardless of their use as a source of antibiotics, vitamins and raw materials for various industrially important chemicals, most fungi and filamentous fungi produce metabolites associated with a range of health risks, both in humans and in animals. The association of filamentous fungi and their metabolites to different negative health conditions in humans and animals, has contributed to the importance of investigating different health risks induced by this family of heterotrophs. This review aims to discuss health risks associated with commonly occurring filamentous fungal species which belong to genera Aspergillus, Penicillium and Fusarium, as well as evaluating their pathogenicity and mycotoxic properties. PMID:28677641

Guidelines for reducing dynamic loads in two-bladed teetering-hub downwind wind turbines

NASA Astrophysics Data System (ADS)

Wright, A. D.; Bir, G. S.; Butterfield, C. D.

1995-06-01

A major goal of the federal Wind Energy Program is the rapid development and validation of structural models to determine loads and response for a wide variety of different wind turbine configurations operating under extreme conditions. Such codes are crucial to the successful design of future advanced wind turbines. In previous papers the authors described steps they took to develop a model of a two-bladed teetering-hub downwind wind turbine using ADAMS (Automatic Dynamic Analysis of Mechanical Systems), as well as comparison of model predictions to test data. In this paper they show the use of this analytical model to study the influence of various turbine parameters on predicted system loads. They concentrate their study on turbine response in the frequency range of six to ten times the rotor rotational frequency (6P to 10P). Their goal is to identify the most important parameters which influence the response of this type of machine in this frequency range and give turbine designers some general design guidelines for designing two-bladed teetering-hub machines to be less susceptible to vibration. They study the effects of such parameters as blade edgewise and flapwise stiffness, tower top stiffness, blade tip-brake mass, low-speed shaft stiffness, nacelle mass momenta of inertia, and rotor speed. They show which parameters can be varied in order to make the turbine less responsive to such atmospheric inputs as wind shear and tower shadow. They then give designers a set of design guidelines in order to show how these machines can be designed to be less responsive to these inputs.

Drops moving along and across a filament

NASA Astrophysics Data System (ADS)

Sahu, Rakesh P.; Sinha-Ray, Suman; Yarin, Alexander; Pourdeyhimi, Behnam

2013-11-01

The present work is devoted to the experimental study of oil drop motion both along and across a filament due to the air jet blowing. In case of drop moving along the filament, phenomena such as drop stick-slip motion, shape oscillations, shedding of a tail along the filament, the tail capillary instability and drop recoil motion were observed which were rationalized in the framework of simplified models. Experiments with cross-flow of the surrounding gas relative to the filament with an oil drop on it were conducted, with air velocity in the range of 7.23 to 22.7 m s-1. The Weber number varied from 2 to 40 and the Ohnesorge number varied from 0.07 to 0.8. The lower and upper critical Weber numbers were introduced to distinguish between the beginning of the drop blowing off the filament and the onset of the bag-stamen breakup. The range of the Weber number between these two critical values is filled with three types of vibrational breakup: V1 (a balloon-like drop being blown off), V2 (a drop on a single stamen being blown off), and V3 (a drop on a double stamen being blown off). The Weber number/Ohnesorge number plane was delineated into domains of different breakup regimes. The work is supported by the Nonwovens Cooperative Research Center (NCRC).

Extending Femtosecond Filamentation of High Power Laser Propagating in the Atmosphere

NASA Astrophysics Data System (ADS)

Eisenmann, Shmuel; Sivan, Yonatan; Fibich, Gadi; Zigler, Arie

2008-06-01

We show experimentally for ultrashort laser pulses propagating in air, that the filamentation distance of intense laser pulses in the atmosphere can be extended and controlled with a simple double-lens setup. Using this method we were able to achieve a 20-fold delay of the filamentation distance of non-chirped 120 fs pulses propagating in air, from 16 m to 330 m. At 330 m, the collapsing pulse is sufficiently powerful to create plasma filaments. We also show that the scatter of the filaments at 330 m can be significantly reduced by tilting the second lens. We derive a simple formula for the filamentation distance, and confirm its agreement with the experimental results. We also observe that delaying the onset of filamentation increases the filament length. To the best of our knowledge, this is the longest distance reported in the literature at which plasma filaments were created and controlled. Finally, we show that the peak power at the onset of collapse is significantly higher with the double-lens setup, compared with the standard negative chirping approach.

Giant quiescent solar filament observed with high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Kuckein, C.; Verma, M.; Denker, C.

2016-05-01

Aims: An extremely large filament was studied in various layers of the solar atmosphere. The inferred physical parameters and the morphological aspects are compared with smaller quiescent filaments. Methods: A giant quiet-Sun filament was observed with the high-resolution Echelle spectrograph at the Vacuum Tower Telescope at Observatorio del Teide, Tenerife, Spain, on 2011 November 15. A mosaic of spectra (ten maps of 100″ × 182″) was recorded simultaneously in the chromospheric absorption lines Hα and Na I D2. Physical parameters of the filament plasma were derived using cloud model (CM) inversions and line core fits. The spectra were complemented with full-disk filtergrams (He I λ10830 Å, Hα, and Ca II K) of the Chromospheric Telescope (ChroTel) and full-disk magnetograms of the Helioseismic and Magnetic Imager (HMI). Results: The filament had extremely large linear dimensions (~817 arcsec), which corresponds to about 658 Mm along a great circle on the solar surface. A total amount of 175119 Hα contrast profiles were inverted using the CM approach. The inferred mean line-of-sight (LOS) velocity, Doppler width, and source function were similar to previous works of smaller quiescent filaments. However, the derived optical thickness was higher. LOS velocity trends inferred from the Hα line core fits were in accord but weaker than those obtained with CM inversions. Signatures of counter-streaming flows were detected in the filament. The largest brightening conglomerates in the line core of Na I D2 coincided well with small-scale magnetic fields as seen by HMI. Mixed magnetic polarities were detected close to the ends of barbs. The computation of photospheric horizontal flows based on HMI magnetograms revealed flow kernels with a size of 5-8 Mm and velocities of 0.30-0.45 km s-1 at the ends of the filament. Conclusions: The physical properties of extremely large filaments are similar to their smaller counterparts, except for the optical thickness, which in

Helicity within the vortex filament model.

PubMed

Hänninen, R; Hietala, N; Salman, H

2016-11-24

Kinetic helicity is one of the invariants of the Euler equations that is associated with the topology of vortex lines within the fluid. In superfluids, the vorticity is concentrated along vortex filaments. In this setting, helicity would be expected to acquire its simplest form. However, the lack of a core structure for vortex filaments appears to result in a helicity that does not retain its key attribute as a quadratic invariant. By defining a spanwise vector to the vortex through the use of a Seifert framing, we are able to introduce twist and henceforth recover the key properties of helicity. We present several examples for calculating internal twist to illustrate why the centreline helicity alone will lead to ambiguous results if a twist contribution is not introduced. Our choice of the spanwise vector can be expressed in terms of the tangential component of velocity along the filament. Since the tangential velocity does not alter the configuration of the vortex at later times, we are able to recover a similar equation for the internal twist angle to that of classical vortex tubes. Our results allow us to explain how a quasi-classical limit of helicity emerges from helicity considerations for individual superfluid vortex filaments.

Helicity within the vortex filament model

PubMed Central

Hänninen, R.; Hietala, N.; Salman, H.

2016-01-01

Kinetic helicity is one of the invariants of the Euler equations that is associated with the topology of vortex lines within the fluid. In superfluids, the vorticity is concentrated along vortex filaments. In this setting, helicity would be expected to acquire its simplest form. However, the lack of a core structure for vortex filaments appears to result in a helicity that does not retain its key attribute as a quadratic invariant. By defining a spanwise vector to the vortex through the use of a Seifert framing, we are able to introduce twist and henceforth recover the key properties of helicity. We present several examples for calculating internal twist to illustrate why the centreline helicity alone will lead to ambiguous results if a twist contribution is not introduced. Our choice of the spanwise vector can be expressed in terms of the tangential component of velocity along the filament. Since the tangential velocity does not alter the configuration of the vortex at later times, we are able to recover a similar equation for the internal twist angle to that of classical vortex tubes. Our results allow us to explain how a quasi-classical limit of helicity emerges from helicity considerations for individual superfluid vortex filaments. PMID:27883029

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…

Multilevel-Dc-Bus Inverter For Providing Sinusoidal And Pwm Electrical Machine Voltages

DOEpatents

Su, Gui-Jia [Knoxville, TN

2005-11-29

A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respective one of the commutation switches, a plurality of dc source connections providing a multi-level dc bus for the full bridge network of commutation switches to produce sinusoidal voltages or PWM signals, and a controller connected for control of said dc source connections and said full bridge network of commutation switches to output substantially sinusoidal voltages to the stator windings. With the invention, the number of semiconductor switches is reduced to m+3 for a multi-level dc bus having m levels. A method of machine control is also disclosed.

Technical, economic and legal aspects of wind energy utilization

NASA Astrophysics Data System (ADS)

Obermair, G. M.; Jarass, L.

Potentially problematical areas of the implementation of wind turbines for electricity production in West Germany are identified and briefly discussed. Variations in wind generator output due to source variability may cause power regulation difficulties in the grid and also raise uncertainties in utility capacity planning for new construction. Catastrophic machine component failures, such as a thrown blade, are hazardous to life and property, while lulls in the resource can cause power regulation capabilities only when grid penetration has reached significant levels. Economically, the lack of actual data from large scale wind projects is cited as a barrier to accurate cost comparisons of wind-derived power relative to other generating sources, although breakeven costs for wind power have been found to be $2000/kW installed capacity, i.e., a marginal cost of $0.10/kW.

A catalytic oligomeric motor that walks along a filament track

NASA Astrophysics Data System (ADS)

Huang, Mu-Jie; Kapral, Raymond

2015-06-01

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described by a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments.

Control system of mutually coupled switched reluctance motor drive of mining machines in generator mode

NASA Astrophysics Data System (ADS)

Ivanov, A. S.; Kalanchin, I. Yu; Pugacheva, E. E.

2017-09-01

One of the first electric motors, based on the use of electromagnets, was a reluctance motor in the XIX century. Due to the complexities in the implementation of control system the development of switched reluctance electric machines was repeatedly initiated only in 1960 thanks to the development of computers and power electronic devices. The main feature of these machines is the capacity to work both in engine mode and in generator mode. Thanks to a simple and reliable design in which there is no winding of the rotor, commutator, permanent magnets, a reactive gate-inductor electric drive operating in the engine mode is actively being introduced into various areas such as car industry, production of household appliances, wind power engineering, as well as responsible production processes in the oil and mining industries. However, the existing shortcomings of switched reluctance electric machines, such as nonlinear pulsations of electromagnetic moment, the presence of three or four phase supply system and sensor of rotor position prevent wide distribution of this kind of electric machines.

C IV Doppler shifts observed in active region filaments

NASA Technical Reports Server (NTRS)

Klimchuk, J. A.

1986-01-01

The Doppler shift properties of 21 active region filaments were studied using C IV Dopplergram data. Most are associated with corridors of weak magnetic field that separate opposite polarity strong fields seen in photospheric magnetograms. A majority of the filaments are relatively blue shifted, although several lie very close to the dividing lines between blue and red shift. Only one filament in the samples is clearly red shifted. A new calibration procedure for Dopplergrams indicates that sizable zero point offsets are often required. The center-to-limb behavior of the resulting absolute Doppler shifts suggests that filament flows are usually quite small. It is possible that they vanish.

Electric field prediction for a human body-electric machine system.

PubMed

Ioannides, Maria G; Papadopoulos, Peter J; Dimitropoulou, Eugenia

2004-01-01

A system consisting of an electric machine and a human body is studied and the resulting electric field is predicted. A 3-phase induction machine operating at full load is modeled considering its geometry, windings, and materials. A human model is also constructed approximating its geometry and the electric properties of tissues. Using the finite element technique the electric field distribution in the human body is determined for a distance of 1 and 5 m from the machine and its effects are studied. Particularly, electric field potential variations are determined at specific points inside the human body and for these points the electric field intensity is computed and compared to the limit values for exposure according to international standards.

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.

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California.

PubMed

Williams, Amy J; Sumner, Dawn Y; Alpers, Charles N; Karunatillake, Suniti; Hofmann, Beda A

2015-08-01

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous

Preserved filamentous microbial biosignatures in the Brick Flat gossan, Iron Mountain, California

USGS Publications Warehouse

Williams, Amy J.; Sumner, Dawn Y.; Alpers, Charles N.; Karunatillake, Suniti; Hofmann, Beda A

2015-01-01

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous

An SVM-based solution for fault detection in wind turbines.

PubMed

Santos, Pedro; Villa, Luisa F; Reñones, Aníbal; Bustillo, Andres; Maudes, Jesús

2015-03-09

Research into fault diagnosis in machines with a wide range of variable loads and speeds, such as wind turbines, is of great industrial interest. Analysis of the power signals emitted by wind turbines for the diagnosis of mechanical faults in their mechanical transmission chain is insufficient. A successful diagnosis requires the inclusion of accelerometers to evaluate vibrations. This work presents a multi-sensory system for fault diagnosis in wind turbines, combined with a data-mining solution for the classification of the operational state of the turbine. The selected sensors are accelerometers, in which vibration signals are processed using angular resampling techniques and electrical, torque and speed measurements. Support vector machines (SVMs) are selected for the classification task, including two traditional and two promising new kernels. This multi-sensory system has been validated on a test-bed that simulates the real conditions of wind turbines with two fault typologies: misalignment and imbalance. Comparison of SVM performance with the results of artificial neural networks (ANNs) shows that linear kernel SVM outperforms other kernels and ANNs in terms of accuracy, training and tuning times. The suitability and superior performance of linear SVM is also experimentally analyzed, to conclude that this data acquisition technique generates linearly separable datasets.

An SVM-Based Solution for Fault Detection in Wind Turbines

PubMed Central

Santos, Pedro; Villa, Luisa F.; Reñones, Aníbal; Bustillo, Andres; Maudes, Jesús

2015-01-01

Research into fault diagnosis in machines with a wide range of variable loads and speeds, such as wind turbines, is of great industrial interest. Analysis of the power signals emitted by wind turbines for the diagnosis of mechanical faults in their mechanical transmission chain is insufficient. A successful diagnosis requires the inclusion of accelerometers to evaluate vibrations. This work presents a multi-sensory system for fault diagnosis in wind turbines, combined with a data-mining solution for the classification of the operational state of the turbine. The selected sensors are accelerometers, in which vibration signals are processed using angular resampling techniques and electrical, torque and speed measurements. Support vector machines (SVMs) are selected for the classification task, including two traditional and two promising new kernels. This multi-sensory system has been validated on a test-bed that simulates the real conditions of wind turbines with two fault typologies: misalignment and imbalance. Comparison of SVM performance with the results of artificial neural networks (ANNs) shows that linear kernel SVM outperforms other kernels and ANNs in terms of accuracy, training and tuning times. The suitability and superior performance of linear SVM is also experimentally analyzed, to conclude that this data acquisition technique generates linearly separable datasets. PMID:25760051

Connections of intermediate filaments with the nuclear lamina and the cell periphery.

PubMed

Katsuma, Y; Swierenga, S H; Marceau, N; French, S W

1987-01-01

We investigated the relationship between intermediate filaments (IFs) and other detergent- and nuclease-resistant filamentous structures of cultured liver epithelial cells (T51B cell line) using whole mount unembedded preparations which were sequentially extracted with Triton X-100 and nucleases. Immunogold labelling and stereoscopic observation facilitated the examination of each filamentous structure and their three-dimensional relationships to each other. After solubilizing phospholipid, nucleic acid and soluble cellular protein, the resulting cytoskeleton preparation consisted of a network of cytokeratin and vimentin IFs linked by 3 nm filaments. The IFs were anchored to and determined the position of the nuclear lamina filaments (NLF) network and the centrioles. The NLF was composed of the nuclear lamina filaments measuring 3-6 nm in diameter which radiated from and anchored to the skeleton of the nuclear pores. The IFs located in the nuclear region appeared to be interwoven with the NLF. At the cell surface, the IFs seemed to be attached to the putative actin filament network. They formed a focally interrupted plexus-like structure at the cell periphery. Fragments of vimentin filaments were found among the filamentous network located at the cell surface, and some filaments terminated blindly there.

Design of a Modular E-Core Flux Concentrating Axial Flux Machine: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Husain, Tausif; Sozer, Yilmaz; Husain, Iqbal

2015-08-24

In this paper a novel E-Core axial flux machine is proposed. The machine has a double-stator, single-rotor configuration with flux-concentrating ferrite magnets and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single-phase and a three-phase version of the E-Core machine. Case studies for a 1.1-kW, 400-rpm machine for both the single-phase and three-phase axial flux machines are presented. The results are verified through 3D finite element analysis. facilitatingmore » simpler construction. This paper presents a single-phase and a three-phase version of the E-Core machine. Case studies for a 1.1-kW, 400-rpm machine for both the single-phase and three-phase axial flux machines are presented. The results are verified through 3D finite element analysis.« less

Practical aspects of the use of three-phase alternating current electric machines in electricity storage system

NASA Astrophysics Data System (ADS)

Ciucur, Violeta

2015-02-01

Of three-phase alternating current electric machines, it brings into question which of them is more advantageous to be used in electrical energy storage system by pumping water. The two major categories among which are given dispute are synchronous and the asynchronous machine. To consider the synchronous machine with permanent magnet configuration because it brings advantages compared with conventional synchronous machine, first by removing the necessary additional excitation winding. From the point of view of loss of the two types of machines, the optimal adjustment of the magnetic flux density is obtained to minimize the copper loss by hysteresis and eddy currents.

Large amplitude oscillatory motion along a solar filament

NASA Astrophysics Data System (ADS)

Vršnak, B.; Veronig, A. M.; Thalmann, J. K.; Žic, T.

2007-08-01

Context: Large amplitude oscillations of solar filaments is a phenomenon that has been known for more than half a century. Recently, a new mode of oscillations, characterized by periodical plasma motions along the filament axis, was discovered. Aims: We analyze such an event, recorded on 23 January 2002 in Big Bear Solar Observatory Hα filtergrams, to infer the triggering mechanism and the nature of the restoring force. Methods: Motion along the filament axis of a distinct buldge-like feature was traced, to quantify the kinematics of the oscillatory motion. The data were fitted by a damped sine function to estimate the basic parameters of the oscillations. To identify the triggering mechanism, morphological changes in the vicinity of the filament were analyzed. Results: The observed oscillations of the plasma along the filament were characterized by an initial displacement of 24 Mm, an initial velocity amplitude of 51 km s-1, a period of 50 min, and a damping time of 115 min. We interpret the trigger in terms of poloidal magnetic flux injection by magnetic reconnection at one of the filament legs. The restoring force is caused by the magnetic pressure gradient along the filament axis. The period of oscillations, derived from the linearized equation of motion (harmonic oscillator) can be expressed as P=π√{2}L/v_Aϕ≈4.4L/v_Aϕ, where v_Aϕ =Bϕ0/√μ_0ρ represents the Alfvén speed based on the equilibrium poloidal field Bϕ0. Conclusions: Combination of our measurements with some previous observations of the same kind of oscillations shows good agreement with the proposed interpretation. Movie to Fig. 1 is only available in electronic form at http://www.aanda.org

Dramatic enhancement of supercontinuum generation in elliptically-polarized laser filaments

PubMed Central

Rostami, Shermineh; Chini, Michael; Lim, Khan; Palastro, John P.; Durand, Magali; Diels, Jean-Claude; Arissian, Ladan; Baudelet, Matthieu; Richardson, Martin

2016-01-01

Broadband laser sources based on supercontinuum generation in femtosecond laser filamentation have enabled applications from stand-off sensing and spectroscopy to the generation and self-compression of high-energy few-cycle pulses. Filamentation relies on the dynamic balance between self-focusing and plasma defocusing – mediated by the Kerr nonlinearity and multiphoton or tunnel ionization, respectively. The filament properties, including the supercontinuum generation, are therefore highly sensitive to the properties of both the laser source and the propagation medium. Here, we report the anomalous spectral broadening of the supercontinuum for filamentation in molecular gases, which is observed for specific elliptical polarization states of the input laser pulse. The resulting spectrum is accompanied by a modification of the supercontinuum polarization state and a lengthening of the filament plasma column. Our experimental results and accompanying simulations suggest that rotational dynamics of diatomic molecules play an essential role in filamentation-induced supercontinuum generation, which can be controlled with polarization ellipticity. PMID:26847427

The Weak Lensing Masses of Filaments between Luminous Red Galaxies

NASA Astrophysics Data System (ADS)

Epps, Seth D.; Hudson, Michael J.

2017-07-01

In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 1013 M⊙ for a stacked filament region 7.1 h-1 Mpc long and 2.5 h-1 Mpc wide. This filament signal is compared with a model based on the three-point galaxy-galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

Molecular gas in high-mass filament WB673

NASA Astrophysics Data System (ADS)

Kirsanova, Maria S.; Salii, Svetlana V.; Sobolev, Andrej M.; Olofsson, Anders Olof Henrik; Ladeyschikov, Dmitry A.; Thomasson, Magnus

2017-12-01

We studied the distribution of dense gas in a filamentary molecular cloud containing several dense clumps. The center of the filament is given by the dense clump WB673. The clumps are high-mass and intermediate-mass starforming regions. We observed CS (2-1), 13CO (1-0), C18O(1-0), and methanol lines at 96 GHz toward WB673 with the Onsala Space Observatory 20-m telescope. We found CS (2-1) emission in the inter-clump medium so the clumps are physically connected and the whole cloud is indeed a filament. Its total mass is 104 M⊙ and mass-to-length ratio is 360M⊙ pc-1 from 13CO (1-0) data. Mass-to-length ratio for the dense gas is 3.4 - 34M⊙ pc-1 from CS (2-1) data. The PV-diagram of the filament is V-shaped. We estimated physical conditions in the molecular gas using methanol lines. Location of the filament on the sky between extended shells suggests that it could be a good example to test theoretical models of formation of the filaments via multiple compression of interstellar gas by supersonic waves.

The multicellular nature of filamentous heterocyst-forming cyanobacteria.

PubMed

Herrero, Antonia; Stavans, Joel; Flores, Enrique

2016-11-01

Cyanobacteria carry out oxygenic photosynthesis, play a key role in the cycling of carbon and nitrogen in the biosphere, and have had a large impact on the evolution of life and the Earth itself. Many cyanobacterial strains exhibit a multicellular lifestyle, growing as filaments that can be hundreds of cells long and endowed with intercellular communication. Furthermore, under depletion of combined nitrogen, filament growth requires the activity of two interdependent cell types: vegetative cells that fix CO2 and heterocysts that fix N2. Intercellular molecular transfer is essential for signaling involved in the regulation of heterocyst differentiation and for reciprocal nutrition of heterocysts and vegetative cells. Here we review various aspects of multicellularity in cyanobacterial filaments and their differentiation, including filament architecture with emphasis on the structures used for intercellular communication; we survey theoretical models that have been put forward to understand heterocyst patterning and discuss the factors that need to be considered for these models to reflect the biological entity; and finally, since cell division in filamentous cyanobacteria has the peculiarity of producing linked instead of independent cells, we review distinct aspects of cell division in these organisms.

Dual stator winding variable speed asynchronous generator: optimal design and experiments

NASA Astrophysics Data System (ADS)

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

2015-06-01

In the present paper is carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behavior in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings to optimal design using a Matlab code. Issue is limited to three phase range of double stator winding cage-induction generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA].

Small wind systems field evaluation. Volume I. Program description. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodge, D.M.; Liske, C.

1982-07-01

A Field Evaluation Program (FEP) was developed in 1978 to assist in the commercialization process for small wind systems. The program is described, and a description is provided of the institutional issues and barriers encountered and measures taken to assist the state and local governments in resolving them. Barriers were found to involve not only government regulations, but also the distribution of costs and benefits of wind technology and the rate of diffusion of knowledge about wind technology. The availability of capital to finance the production and purchase of wind machines, and the training of qualified dealers and service personnelmore » were also considerable problem areas. (LEW)« less

Snaking Filament Eruption

NASA Image and Video Library

2014-11-14

A filament (which at one point had an eerie similarity to a snake) broke away from the sun and out into space (Nov. 1, 2014). The video covers just over three hours of activity. This kind of eruptive event is called a Hyder flare. These are filaments (elongated clouds of gases above the sun's surface) that erupt and cause a brightening at the sun's surface, although no active regions are in that area. It did thrust out a cloud of particles but not towards Earth. The images were taken in the 304 Angstrom wavelength of extreme UV light. Credit: NASA/Solar Dynamics Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

The influence of filament temperature and oxygen concentration on tungsten oxide nanostructures by hot filament metal oxide deposition

NASA Astrophysics Data System (ADS)

Lou, J.; Ye, B. J.; Weng, H. M.; Du, H. J.; Wang, Z. B.; Wang, X. P.

2008-08-01

Tungsten oxide (WOx) nanostructures were prepared by a hot filament chemical vapour deposition system and the temperature of the hot tungsten filaments was changed by steps of degrees. The morphology and average growth rate were indicated by scanning electron microscopy which showed that the morphology was highly related to the filament temperature (Tf) and the distance between the filaments and the polished Si (1 0 0) substrates (df). The influence of Tf on the crystalline nature was studied by x-ray diffraction and Raman spectroscopy. The evolution of stoichiometry and types of defects was indicated by x-ray photoelectron spectroscopy and slow positron implantation spectroscopy. When Tf was up to 1750 °C, tungsten oxide nanostructure was synthesized. A turning point of Tf was found at which the nature of crystallinity and of stoichiometry was the best. As Tf increased to 2100 °C or df decreased, the film crystallinity decreased; correspondingly, the component ratio of stoichiometry WO3 decreased and lots of vacancy agglomerates were present. In order to develop the chemical phase from substoichiometry to stoichiometry, the oxygen gas concentration in the mixture gas during deposition should be raised to an appropriate level.

Cofilin-2 controls actin filament length in muscle sarcomeres

PubMed Central

Kremneva, Elena; Makkonen, Maarit H.; Skwarek-Maruszewska, Aneta; Gateva, Gergana; Michelot, Alphee; Dominguez, Roberto; Lappalainen, Pekka

2014-01-01

SUMMARY ADF/cofilins drive cytoskeletal dynamics by promoting the disassembly of ‘aged’ ADP-actin filaments. Mammals express several ADF/cofilin isoforms, but their specific biochemical activities and cellular functions have not been studied in detail. Here we demonstrate that the muscle-specific isoform cofilin-2 promotes actin filament disassembly in sarcomeres to control the precise length of thin filaments in the contractile apparatus. In contrast to other isoforms, cofilin-2 efficiently binds and disassembles both ADP- and ATP/ADP-Pi-actin filaments. We mapped surface-exposed cofilin-2-specific residues required for ATP-actin binding and propose that these residues function as an ‘actin nucleotide-state sensor’ among ADF/cofilins. The results suggest that cofilin-2 evolved specific biochemical and cellular properties allowing it to control actin dynamics in sarcomeres, where filament pointed ends may contain a mixture of ADP- and ATP/ADP-Pi-actin subunits. Our findings also offer a rationale for why cofilin-2 mutations in humans lead to myopathies. PMID:25373779

Filament capturing with the multimaterial moment-of-fluid method*

DOE PAGES

Jemison, Matthew; Sussman, Mark; Shashkov, Mikhail

2015-01-15

A novel method for capturing two-dimensional, thin, under-resolved material configurations, known as “filaments,” is presented in the context of interface reconstruction. This technique uses a partitioning procedure to detect disconnected regions of material in the advective preimage of a cell (indicative of a filament) and makes use of the existing functionality of the Multimaterial Moment-of-Fluid interface reconstruction method to accurately capture the under-resolved feature, while exactly conserving volume. An algorithm for Adaptive Mesh Refinement in the presence of filaments is developed so that refinement is introduced only near the tips of filaments and where the Moment-of-Fluid reconstruction error is stillmore » large. Comparison to the standard Moment-of-Fluid method is made. As a result, it is demonstrated that using filament capturing at a given resolution yields gains in accuracy comparable to introducing an additional level of mesh refinement at significantly lower cost.« less

Observation of conducting filament growth in nanoscale resistive memories

NASA Astrophysics Data System (ADS)

Yang, Yuchao; Gao, Peng; Gaba, Siddharth; Chang, Ting; Pan, Xiaoqing; Lu, Wei

2012-03-01

Nanoscale resistive switching devices, sometimes termed memristors, have recently generated significant interest for memory, logic and neuromorphic applications. Resistive switching effects in dielectric-based devices are normally assumed to be caused by conducting filament formation across the electrodes, but the nature of the filaments and their growth dynamics remain controversial. Here we report direct transmission electron microscopy imaging, and structural and compositional analysis of the nanoscale conducting filaments. Through systematic ex-situ and in-situ transmission electron microscopy studies on devices under different programming conditions, we found that the filament growth can be dominated by cation transport in the dielectric film. Unexpectedly, two different growth modes were observed for the first time in materials with different microstructures. Regardless of the growth direction, the narrowest region of the filament was found to be near the dielectric/inert-electrode interface in these devices, suggesting that this region deserves particular attention for continued device optimization.

Lightweight MgB2 superconducting 10 MW wind generator

NASA Astrophysics Data System (ADS)

Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

2016-02-01

The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

Control of multiple filamentation in air

NASA Astrophysics Data System (ADS)

Fibich, Gadi; Eisenmann, Shmuel; Ilan, Boaz; Zigler, Arie

2004-08-01

In this Letter we provide what is believed to be the first experimental evidence of suppression of the number of filaments for high-intensity laser pulses propagating in air by beam astigmatism. We also show that the number, pattern, and spatial stability of the filaments can be controlled by varying the angle that a focusing lens makes with the axial direction of propagation. This new methodology can be useful for applications involving atmospheric propagation, such as remote sensing.

Contribution of actin filaments to the global compressive properties of fibroblasts.

PubMed

Ujihara, Yoshihiro; Nakamura, Masanori; Miyazaki, Hiroshi; Wada, Shigeo

2012-10-01

Actin filaments are often regarded as tension-bearing components. Here, we examined the effects of actin filaments on global compressive properties of cells experimentally and numerically. Fibroblasts were harvested from the patellar tendon of a mature Japanese white rabbit and treated with cytochalasin D to depolymerize the actin filaments. Intact cells and cells with disrupted actin filaments were subjected to the compressive tests. Each floating cell was held between the cantilever and compressive plates and compressed by moving the compressive plate with a linear actuator to obtain a load-deformation curve under quasi-static conditions. The experimental results demonstrated that the initial stiffness of a cell with disrupted actin filaments decreased by 51%. After the experiments, we simulated the compressive test of cells with/without bundles of actin filaments. A bundle of actin filaments was modeled as a tension-bearing component that generates a force based on Hooke's law only when it was elongated. By contrast, if it was shortened, it was assumed to exert no force. The computational results revealed that the alignment of bundles of actin filaments significantly affected the cell stiffness. In addition, the passive reorientation of bundles of actin filaments perpendicular to the compression induced an increase in the resistance to the vertical elongation of a cell and thereby increased the cell stiffness. These results clearly indicated that bundles of actin filaments contribute to the compressive properties of a cell, even if they are tension-bearing components. Copyright © 2012 Elsevier Ltd. All rights reserved.

A catalytic oligomeric motor that walks along a filament track

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Mu-Jie, E-mail: mjhuang@chem.utoronto.ca; Kapral, Raymond, E-mail: rkapral@chem.utoronto.ca

Most biological motors in the cell execute chemically powered conformational changes as they walk on biopolymer filaments in order to carry out directed transport functions. Synthetic motors that operate in a similar manner are being studied since they have the potential to perform similar tasks in a variety of applications. In this paper, a synthetic nanomotor that moves along a filament track, without invoking motor conformational changes, is constructed and its properties are studied in detail. The motor is an oligomer comprising three linked beads with specific binding properties. The filament track is a stiff polymer chain, also described bymore » a linear chain of linked coarse-grained molecular groups modeled as beads. Reactions on the filament that are catalyzed by a motor bead and use fuel in the environment, in conjunction within the binding affinities of the motor beads to the filament beads, lead to directed motion. The system operates out of equilibrium due to the state of the filament and supply of fuel. The motor, filament, and surrounding medium are all described at microscopic level that permits a full analysis of the motor motion. A stochastic model that captures the main trends seen in the simulations is also presented. The results of this study point to some of the key features that could be used to construct nanomotors that undergo biased walks powered by chemical reactions on filaments.« less

SYMPATHETIC FILAMENT ERUPTIONS CONNECTED BY CORONAL DIMMINGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang Yunchun; Yang Jiayan; Hong Junchao

2011-09-10

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

Development of a compact filament-discharge multi-cusp H- ion source.

PubMed

Jia, XianLu; Zhang, TianJue; Zheng, Xia; Qin, JiuChang

2012-02-01

A 14 MeV medical cyclotron with the external ion source has been designed and is being constructed at China Institute of Atomic Energy. The H(-) ion will be accelerated by this machine and the proton beam will be extracted by carbon strippers in dual opposite direction. The compact multi-cusp H(-) ion source has been developed for the cyclotron. The 79.5 mm long ion source is 48 mm in diameter, which is consisting of a special shape filament, ten columns of permanent magnets providing a multi-cusp field, and a three-electrode extraction system. So far, the 3 mA∕25 keV H(-) beam with an emittance of 0.3 π mm mrad has been obtained from the ion source. The paper gives the design details and the beam test results. Further experimental study is under way and an extracted beam of 5 mA is expected.

Short time ahead wind power production forecast

NASA Astrophysics Data System (ADS)

Sapronova, Alla; Meissner, Catherine; Mana, Matteo

2016-09-01

An accurate prediction of wind power output is crucial for efficient coordination of cooperative energy production from different sources. Long-time ahead prediction (from 6 to 24 hours) of wind power for onshore parks can be achieved by using a coupled model that would bridge the mesoscale weather prediction data and computational fluid dynamics. When a forecast for shorter time horizon (less than one hour ahead) is anticipated, an accuracy of a predictive model that utilizes hourly weather data is decreasing. That is because the higher frequency fluctuations of the wind speed are lost when data is averaged over an hour. Since the wind speed can vary up to 50% in magnitude over a period of 5 minutes, the higher frequency variations of wind speed and direction have to be taken into account for an accurate short-term ahead energy production forecast. In this work a new model for wind power production forecast 5- to 30-minutes ahead is presented. The model is based on machine learning techniques and categorization approach and using the historical park production time series and hourly numerical weather forecast.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1996-11-01

The National Renewable Energy Laboratory has recently developed the ability to predict turbine loads and responses for machines undergoing variable-speed operation. The wind industry has debated the potential benefits of operating wind turbine sat variable speeds for some time. Turbine system dynamic responses (structural response, resonance, and component interactions) are an important consideration for variable-speed operation of wind turbines. The authors have implemented simple, variable-speed control algorithms for both the FAST and ADAMS dynamics codes. The control algorithm is a simple one, allowing the turbine to track the optimum power coefficient (C{sub p}). The objective of this paper is tomore » show turbine loads and responses for a particular two-bladed, teetering-hub, downwind turbine undergoing variable-speed operation. The authors examined the response of the machine to various turbulent wind inflow conditions. In addition, they compare the structural responses under fixed-speed and variable-speed operation. For this paper, they restrict their comparisons to those wind-speed ranges for which limiting power by some additional control strategy (blade pitch or aileron control, for example) is not necessary. The objective here is to develop a basic understanding of the differences in loads and responses between the fixed-speed and variable-speed operation of this wind turbine configuration.« less

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

NASA Astrophysics Data System (ADS)

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

1992-05-01

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.

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.

Merging Clusters, Cluster Outskirts, and Large Scale Filaments

NASA Astrophysics Data System (ADS)

Randall, Scott; Alvarez, Gabriella; Bulbul, Esra; Jones, Christine; Forman, William; Su, Yuanyuan; Miller, Eric D.; Bourdin, Herve; Scott Randall

2018-01-01

Recent X-ray observations of the outskirts of clusters show that entropy profiles of the intracluster medium (ICM) generally flatten and lie below what is expected from purely gravitational structure formation near the cluster's virial radius. Possible explanations include electron/ion non-equilibrium, accretion shocks that weaken during cluster formation, and the presence of unresolved cool gas clumps. Some of these mechanisms are expected to correlate with large scale structure (LSS), such that the entropy is lower in regions where the ICM interfaces with LSS filaments and, presumably, the warm-hot intergalactic medium (WHIM). Major, binary cluster mergers are expected to take place at the intersection of LSS filaments, with the merger axis initially oriented along a filament. We present results from deep X-ray observations of the virialization regions of binary, early-stage merging clusters, including a possible detection of the dense end of the WHIM along a LSS filament.

Tailoring femtosecond laser pulse filamentation using plasma photonic lattices

NASA Astrophysics Data System (ADS)

Suntsov, Sergiy; Abdollahpour, Daryoush; Papazoglou, Dimitrios G.; Panagiotopoulos, Paris; Couairon, Arnaud; Tzortzakis, Stelios

2013-07-01

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

Preserved Filamentous Microbial Biosignatures in the Brick Flat Gossan, Iron Mountain, California

PubMed Central

Sumner, Dawn Y.; Alpers, Charles N.; Karunatillake, Suniti; Hofmann, Beda A.

2015-01-01

Abstract A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses

ERUPTION OF A SOLAR FILAMENT CONSISTING OF TWO THREADS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bi Yi; Jiang Yunchun; Li Haidong

The trigger and driving mechanism for the eruption of a filament consisting of two dark threads was studied with unprecedented high cadence and resolution of He II 304 A observations made by the Atmospheric Imagining Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the observations made by the Solar Magnetic Activity Research Telescope and the Extreme Ultraviolet Imager (EUVI) telescope on board the Solar Terrestrial Relations Observatory Ahead (STEREO-A). The filament was located at the periphery of the active region NOAA 11228 and erupted on 2011 June 6. At the onset of the eruption, a turbulent filament threadmore » was found to be heated and to elongate in stride over a second one. After it rose slowly, most interestingly, the elongating thread was driven to contact and interact with the second one, and it then erupted with its southern leg being wrapped by a newly formed thread produced by the magnetic reconnection between fields carried by the two threads. Combining the observations from STEREO-A/EUVI and SDO/AIA 304 A images, the three-dimensional shape of the axis of the filament was obtained and it was found that only the southern leg of the eruptive filament underwent rotation. We suggest that the eruption was triggered by the reconnection of the turbulent filament thread and the surrounding magnetic field, and that it was mainly driven by the kink instability of the southern leg of the eruptive filament that possessed a more twisted field introduced by the reconnection-produced thread.« less